Peeling method and method of manufacturing semiconductor device

ABSTRACT

There is provided a peeling method capable of preventing a damage to a layer to be peeled. Thus, not only a layer to be peeled having a small area but also a layer to be peeled having a large area can be peeled over the entire surface at a high yield. Processing for partially reducing contact property between a first material layer ( 11 ) and a second material layer ( 12 ) (laser light irradiation, pressure application, or the like) is performed before peeling, and then peeling is conducted by physical means. Therefore, sufficient separation can be easily conducted in an inner portion of the second material layer ( 12 ) or an interface thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.13/466,212, filed May 8, 2012, now allowed, which is a continuation ofU.S. application Ser. No. 12/477,966, filed Jun. 4, 2009, now U.S. Pat.No. 8,338,198, which is a continuation of U.S. application Ser. No.12/016,274, filed Jan. 18, 2008, now U.S. Pat. No. 7,825,002, which is acontinuation of U.S. application Ser. No. 10/218,042, filed Aug. 14,2002, now U.S. Pat. No. 7,351,300, which claims the benefit of a foreignpriority application filed in Japan as Serial No. 2001-251870 on Aug.22, 2001, all of which are incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device having a circuitcomposed of thin film transistors (hereinafter referred to as TFTs) anda manufacturing method thereof. The present invention relates to anelectro-optical device which is represented by, for example, a liquidcrystal display panel and an electronic device on which such anelectro-optical device is mounted as a part.

Note that a semiconductor device in this specification indicates ageneral device functioning by utilizing semiconductor characteristics,which includes an electro-optical device, a light emitting device, asemiconductor circuit, and an electronic device.

2. Description of the Related Art

In recent years, a technique of constructing a thin film transistor(TFT) using a semiconductor thin film (about several to several hundrednm in thickness) formed on a substrate having an insulating surface hasdrawn attention. The thin film transistor is widely applied to anelectronic device such as an IC or an electro-optical device. Inparticular, the development for the thin film transistor as a switchingelement of an image display device is urgently necessary.

Various applications utilizing such an image display device areexpected, and particularly the utilization to a mobile device is noted.Currently, a glass substrate or a quartz substrate is used for formingthe TFT in many cases. However, there is a defect that they are easy tocrack and heavy. In addition, in the case of mass production, it isdifficult to use a large scale glass substrate or quartz substrate andthese substrates are not suitable. Thus, it is attempted to form a TFTelement on a flexible substrate, typically, a flexible plastic film.

However, the plastic film has a low heat resistance, so that it isnecessary to reduce a maximum temperature of a process. As a result,under the current circumstances, a TFT having a preferable electricalcharacteristic cannot be formed on the plastic film as compared with thecase where the glass substrate is used. Therefore, a high performanceliquid crystal display device and light emitting element with theplastic film are not realized.

Also, a peeling method of peeling a layer to be peeled which is locatedover a substrate through a separate layer, from the substrate hasalready been proposed. According to the technique described in, forexample, JP 10-125929 A or JP 10-125931 A, the separate layer made ofamorphous silicon (or polysilicon) is provided on the substrate, andlaser light is irradiated thereto through the substrate to releasehydrogen contained in the amorphous silicon. As a result, gaps areproduced in the separate layer, thereby separating the layer to bepeeled from the substrate. In addition, according to JP 10-125930 A, itis described that a layer to be peeled (which is called a layer to betransferred in this document) is bonded to a plastic film to complete aliquid crystal display device using the above technique.

However, according to the above method, it is essential to use substratehaving high transparent property. In addition, it is necessary toperform a laser light irradiation with relatively high energy enough totransmit laser light through the substrate and to release hydrogencontained in the amorphous silicon. Thus, there is a problem in that thelayer to be peeled is damaged. Further, according to the above method,in the case where an element is manufactured on the separate layer,when, for example, heat treatment with a high temperature is performedin an element manufacturing process, hydrogen contained in the separatelayer is diffused to reduce the concentration thereof. Thus, even whenthe laser light is irradiated to the separate layer, there is apossibility that peeling is not sufficiently performed. Therefore, whenthe amount of hydrogen contained in the separate layer is kept, there isa problem in that a process performed after the formation of theseparate layer is limited. Furthermore, in the above document, it isdescribed that a light shielding layer or a reflective layer is providedto prevent the damage to the layer to be peeled. However, in this case,it is difficult to manufacture a transmission liquid crystal displaydevice. In addition, in the above method, it is difficult to peel thelayer to be peeled having a large area.

Also, according to a conventional peeling method, a thin film is used asa layer for producing a peeling phenomenon (separate layer or the like).Thus, when nonuniformity of a film thickness is caused in the substrate,contact property between the separate layer and the substrate becomesnonuniform and poor peeling such as insufficient peeling or cracking ina substrate is easily caused at the time of peeling.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above problems. Anobject of the present invention is therefore to provide a peeling methodin which a layer to be peeled is not damaged and not only a layer to bepeeled having a small area but also a layer to be peeled having a largearea can be peeled without causing poor peeling over the entire surface.

Also, an object of the present invention is to provide a peeling methodwhich is not limited by a heat treatment temperature, a kind ofsubstrate, and the like at the formation of the layer to be peeled.

Also, an object of the present invention is to provide a semiconductordevice in which the layer to be peeled is bonded to various base membersto reduce its weight and a manufacturing method thereof. Particularly,an object of the present invention is to provide a semiconductor devicein which various elements (thin film diode, a photoelectric conversionelement having a silicon PIN junction (solar battery, a sensor, or thelike), and a silicon resistance element) represented by a TFT are bondedto a flexible film to reduce its weight and a manufacturing methodthereof.

The present inventors conducted a number of tests and discussions. Afirst material layer is provided on a substrate and a second materiallayer is provided in contact with the first material layer. Then, a filmis formed on the second material layer or heat treatment is performed at500° C. or higher thereon, and internal stresses of the respective filmsare measured. As a result, the first material layer has tensile stressand the second material layer has compression stress. With respect to alaminate of the first material layer and the second material layer, atrouble, such as film peeling is not caused in a process. In addition,clean separation can be easily performed in an inner portion of thesecond material layer or at an interface thereof by physical means,typically, the application of mechanical force, for example, peeling bythe hand of a person.

That is, bonding force between the first material layer and the secondmaterial layer has a sufficient strength to be resistant to separationby heat energy. However, there is stress distortion between the firstmaterial layer having tensile stress and the second material layerhaving compression stress immediately before peeling. Thus, the laminateof the first material layer and the second material layer is sensitiveto mechanical energy, thereby causing peeling. The present inventorsfound that a peeling phenomenon is deeply relevant to internal stress ofa film. Thus, a peeling process of conducting peeling by utilizing theinternal stress of the film is called a stress peel off process.

Also, it is important to make a lead such that a peeling phenomenon iseasy to occur before peeling. Thus, preprocessing for selectively(partially) reducing the contact property is performed, therebypreventing poor peeling and further improving a yield.

That is, the following is considered. A region having a small filmthickness is easy to form in an outer edge of a substrate as comparedwith a central region thereof. If the film thickness is small, a regionhaving high contact property to the substrate is produced. Thus, a filmin such a region becomes resistant to peeling. Only the vicinity of theouter edge of the substrate with the high contact property is scannedwith laser light. Or, a needle is vertically pressed against the thinfilm and a load is applied to the needle. With this state, the needle ismoved along the outer edge of the substrate to scratch it, and thenpeeling is conducted. Therefore, insufficient peeling can be prevented.

Also, it is desirable that peeling is started from the vicinity of theregion for which the above preprocessing is performed.

Also, when the above preprocessing is performed before peeling, theinsufficient peeling is prevented and the material layers which are notpeeled can be peeled. That is, it is possible that a margin with respectto the first material layer or the second material layer, for example,the variety of materials is increased and a range of the filmthicknesses is extended.

According to a constitution of the present invention relating to apeeling method disclosed in this specification, there is provided apeeling method of peeling a layer to be peeled from a substrate,characterized by comprising:

providing a first material layer on the substrate, and forming a layerto be peeled which is composed of a laminate including at least a secondmaterial layer which is in contact with the first material layer, overthe substrate to which the first material layer is provided;

performing processing for partially reducing contact property betweenthe first material layer and the second material layer; and

then peeling the layer to be peeled from the substrate to which thefirst to material layer is provided by physical means at one of an innerportion and an interface of the second material layer.

Also, according to the above constitution, the first material layer ischaracterized by having tensile stress of 1 dyne/cm² to 1×10¹⁰ dyne/cm².As long as a material having tensile stress of the above range is used,it is not particularly limited. Thus, a layer made of any one of ametallic material (Ti, Al, Ta, W, Mo, Cu, Cr, Nd, Fe, Ni, Co, Zr, Zn,Ru, Rh, Pd, Os, Ir, Pt, or the like), a semiconductor material (forexample, Si or Ge), an insulating material, and an organic material, ora laminate of these materials can be used for the first material layer.Note that, when heat treatment is performed for a film having tensilestress larger than 1 dyne/cm² to 1×10¹⁰ dyne/cm², peeling is easy tooccur.

Also, according to the above constitution, the second material layer ischaracterized by having compression stress of −1 dyne/cm² to −1×10¹⁰dyne/cm². When a material having compression stress of the above rangeis used, it is particularly not limited. Thus, a layer made of any oneof a metallic material (Ti, Al, Ta, W, Mo, Cu, Cr, Nd, Fe, Ni, Co, Zr,Zn, Ru, Rh, Pd, Os, Ir, Pt, and the like), a semiconductor material (forexample, Si or Ge) an insulating material, and an organic material, or alaminate of these materials can be used for the second material layer.Note that, when heat treatment is performed for a film havingcompression stress larger than −1×10¹⁰ dyne/cm², peeling is easy tooccur.

Also, even if compression stress is produced immediately afterformation, a material having tensile stress at a state immediatelybefore peeling can be used for the first material layer.

Also, according to the above constitution, another layer, for example,an insulating layer or a metallic layer may be provided between thesubstrate and the first material layer to improve the contact property.In order to simplify a process, it is preferable that the first materiallayer is formed on the substrate.

Also, according to the above constitution, in order to promote peeling,heat treatment or laser light irradiation may be conducted after bondingof the support. In this case, a material which absorbs laser light maybe selected for the first material layer and the first material layer isheated to change internal stress of the film, thereby being easy topeel. When laser light is utilized, a transparent substrate is used.

Note that the physical means in this specification is means understoodnot in chemistry but in physics, specifically indicates dynamic means ormechanical means having a process which can be replaced by a dynamiclaw, and indicates means for changing some dynamic energy (mechanicalenergy).

Also, peeling may be performed after a support is bonded through bondinglayer. According to another constitution of the present inventionrelating to a peeling method disclosed in this specification, there isprovided a peeling method of peeling a layer to be peeled from asubstrate, characterized by comprising:

providing a first material layer on the substrate and forming a layer tobe peeled which is composed of a laminate including at least a secondmaterial layer which is in contact with the first material layer, overthe substrate to which the first material layer is provided;

performing processing for partially reducing contact property betweenthe first material layer and the second material layer;

then bonding a support to the layer to be peeled; and

peeling the layer to be peeled to which the support is bonded from thesubstrate to which the first material layer is provided by physicalmeans at one of an inner portion and an interface of the second materiallayer.

Also, according to the above constitutions, the method is characterizedin that the peeling by the physical means is conducted from a region forwhich the processing for reducing the contact property is performed.

Also, according to the above constitutions, the method is characterizedin that the processing for partially reducing the contact property isthe processing for partially irradiating laser light to one of the firstmaterial layer and the second material layer along an outer edge of thesubstrate, or the processing for locally applying a pressure fromexternal along the outer edge of the substrate to damage an innerportion of the second material layer or a portion of an interfacethereof.

Also, according to the present invention, not only a transparentsubstrate but also all substrates, for example, a glass substrate, aquartz substrate, a semiconductor substrate, a ceramic substrate, and ametallic substrate can be used and the layer to be peeled which isprovided over the substrate can be peeled.

Also, when the processing for partially reducing the contact propertyaccording to the present invention is performed before peeling using aknown peeling method, the layer to be peeled provided which is over thesubstrate can be bonded (transferred) to a transfer body to manufacturea semiconductor device. A method of manufacturing a semiconductor deviceaccording to the present invention includes the steps of:

forming a layer to be peeled which includes an element on a substrate;

bonding a support to the layer to be peeled which includes the elementand then peeling the support from the substrate by physical means; and

bonding a transfer body to the layer to be peeled which includes theelement to sandwich the element between the support and the transferbody,

characterized in that processing for partially reducing contact propertybetween the substrate and the layer to be peeled is performed before thepeeling.

Also, according to the above constitution, the peeling by the physicalmeans is produced from a region for which the processing for reducingthe contact property is performed.

Also, according to the above constitution, the processing for partiallyreducing the contact property is the processing for partiallyirradiating laser light to the first material layer or the secondmaterial layer along the outer edge of the substrate, or the processingfor locally applying a pressure from external along the outer edge ofthe substrate to damage an inner portion of the second material layer ora portion of an interface thereof.

Also, according to the above constitution, the peeling by the physicalmeans may be conducted by blowing a gas onto an end surface of thesubstrate.

Also, according to the above constitution, the peeling by the physicalmeans may be conducted by blowing a gas onto an end surface of thesubstrate together with irradiation of laser light.

Also, according to the above constitution, the peeling by the physicalmeans may be conducted by blowing the gas onto the end surface of thesubstrate together with scanning using the laser light from the regionfor which the processing for reducing the contact property is performed.

Also, according to the above respective constitutions, a heated gas maybe used, and it is preferable that the gas is an inert gas, typically, anitrogen gas.

Also, according to the above respective constitutions with respect tothe method of manufacturing the semiconductor device, the element is athin film transistor using a semiconductor layer as an active layer. Thesemiconductor layer is characterized by being a semiconductor layerhaving a crystalline structure which obtained by crystallizing asemiconductor having an amorphous structure by heat treatment or laserlight irradiation processing.

Note that the transfer body in this specification is bonded to the layerto be peeled after peeling, is not particularly limited, and may be abase member made of any composition such as plastic, glass, metal, orceramics. In addition, the support in this specification is bonded tothe layer to be peeled at peeling by the physical means, is notparticularly limited, and may be a base member made of any compositionsuch as plastic, glass, metal, or ceramics. In addition, the shape ofthe transfer body and the shape of the support are not particularlylimited, they may have a flat surface or a curved surface, may beflexible, or may be formed in a film shape. In addition, when weightreduction is the highest priority, a film-shaped plastic substrate, forexample, a plastic substrate made of polyethylene terephthalate (PET),polyether sulfone (PES), polyethylene naphthalate (PEN), polycarbonate(PC), nylon, polyether etherketone (PEEK), polysulfone (PSF), polyetherimide (PEI), polyallylate (PAR), polybutylene terephthalate (PBT), orthe like is preferable.

According to the above respective constitutions with respect to themethod of manufacturing the semiconductor device, when a liquid crystaldisplay device is manufactured, it is preferable that the support isused as a counter substrate and bonded to the layer to be peeled using asealing member as a bonding layer. In this case, the element provided tothe layer to be peeled has a pixel electrode. A liquid crystal materialis filled into a space between the pixel electrode and the countersubstrate.

Also, according to the above respective constitutions with respect tothe method of manufacturing the semiconductor device, when a lightemitting device represented by an EL light emitting device ismanufactured, it is preferable that the support is used as a sealingmember. Thus, a light emitting element is completely shielded fromexternal so as to prevent entrance of a substance such as moisture oroxygen which promotes deterioration of an organic compound layer fromexternal. In addition, when weight reduction is the highest priority, afilm-shaped plastic substrate is preferable. However, an effect forpreventing entrance of a substance is such as moisture or oxygen whichpromotes deterioration of an organic compound layer from external issmall. Thus, for example, a single layer made of a material selectedfrom aluminum nitride (AlN), aluminum nitride oxide (AlN_(X)O_(Y)(X>Y)), aluminum oxynitride (AlN_(X)O_(Y) (X<Y)), aluminum oxide(Al₂O₃), and beryllium oxide (BeO), or a laminate of those is preferablyprovided to the support which is the plastic substrate to obtain astructure for sufficiently preventing entrance of a substance such asmoisture or oxygen which promotes deterioration of an organic compoundlayer from external. Note that, when aluminum nitride oxide(AlN_(X)O_(Y) (X>Y)) is used, it is desirable that a concentration ofnitrogen contained in the film is 10 atoms % to 80 atoms %.

Also, when the light emitting device represented by the EL lightemitting device is manufactured, as in the case of the support, it ispreferable that a single layer made of a material selected from aluminumnitride (AlN), aluminum nitride oxide (AlN_(X)O_(Y) (X>Y)), aluminumoxynitride (AlN_(X)O_(Y) (X<Y)), aluminum oxide (Al₂O₃), and berylliumoxide (BeO), or a laminate of those is preferably provided to thetransfer body which is the plastic substrate to sufficiently prevententrance of a substance such as moisture or oxygen which promotesdeterioration of an organic compound layer from external. In addition,those films have very high transparent property and thus do not hinderlight emission by a light emitting element.

Note that the internal stress of the film in this specificationindicates, in the case where an arbitrary section is assumed in an innerportion of a film formed on a substrate, stress per unit section whichis exerted from one side of the section to the other side thereof. Itcan be said that the internal stress is necessarily produced more orless in a thin film formed by vacuum evaporation, sputtering, vaporphase growth, or the like. The maximum value reaches 10⁹ N/m². Theinternal stress value is changed depending on a material of a thin film,a substance composing a substrate, a formation condition of the thinfilm, and the like. In addition, the internal stress value is alsochanged by heat treatment.

Also, a state in the case where a direction of stress exerted on acounter through a unit section perpendicular to the surface of asubstrate is a tensile direction is a tensile state and internal stressat this state is called tensile stress. In addition, a state in the casewhere the direction of the stress is a pressing direction is acompression state and internal stress at this state is calledcompression stress. Note that, in the cases of a graph and a table inthis specification, the tensile stress is indicated to be positive (+)and the compression tensile is indicated to be negative (−).

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A to 1D are explanatory views of Embodiment Mode 1;

FIGS. 2A to 2C are explanatory views of Embodiment Mode 2;

FIGS. 3A to 3D are explanatory views of Embodiment Mode 3;

FIGS. 4A to 4C are explanatory views of a test;

FIGS. 5A to 5D are sectional views showing steps of manufacturing anactive matrix substrate;

FIGS. 6A to 6C are sectional views showing steps of manufacturing theactive matrix substrate;

FIG. 7 is a sectional view showing the active matrix substrate;

FIGS. 8A to 8D are explanatory views of Embodiment 2;

FIGS. 9A to 9C are explanatory views of Embodiment 2;

FIG. 10 shows a liquid crystal module;

FIGS. 11A to 11D are explanatory views of Embodiment 4;

FIGS. 12A and 12B are explanatory views of Embodiment 5;

FIG. 13 is an explanatory view of Embodiment 5;

FIG. 14 is an explanatory view of Embodiment 6;

FIGS. 15A to 15F show examples of electronic devices;

FIGS. 16A to 16C show examples of electronic devices;

FIGS. 17A to 17C are explanatory views of a comparison example in atest; and

FIG. 18 is a graph indicating transmittances of an AlN film and an AlNOfilm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment modes of the present invention will be described below.

Embodiment Mode 1

Hereinafter, a typical peeling order according to the present inventionwill be briefly described using FIGS. 1A to 1D.

In FIG. 1A, reference numeral 10 denotes a substrate, 11 denotes a firstmaterial layer having tensile stress, 12 denotes a second material layerhaving compression stress, and 13 denotes a layer to be peeled.

In FIG. 1A, a glass substrate, a quartz substrate, a ceramic substrate,or the like can be used as the substrate 10. In addition, a siliconsubstrate, a metallic substrate, or a stainless steel substrate may bealternatively used.

First, as shown in FIG. 1A, the first material layer 11 is formed on thesubstrate 10. The first material layer 11 may have compression stress ortensile stress immediately after the formation. It is important that thefirst material layer is formed from a material with which a trouble suchas peeling is not caused by heat treatment or laser light irradiation atthe formation of the layer to be peeled and which has tensile stress ata range of 1 dyne/cm² to 1×10¹⁰ dyne/cm² immediately after the formationof the layer to be peeled. As a typical example, there is a single layerwhich is made of an element selected from W, WN, TiN, and TiW, or analloy material or a compound material which contains mainly the element,or a laminate thereof.

Next, the second material layer 12 is formed on the first material layer11. It is important that the second material layer 12 is formed from amaterial with which a trouble such as peeling is not caused by heattreatment or laser light irradiation at the formation of the layer to bepeeled and which has compression stress at a range of 1 dyne/cm² to1×10¹⁰ dyne/cm² immediately after the formation of the layer to bepeeled. As a typical example for the second material layer 12, there issilicon oxide, silicon oxynitride, a metallic oxide material, or alaminate of those. Note that the second material layer 12 may be formedby using any film formation method such as a sputtering method, a plasmaCVD method, or an applying method.

In the present invention, it is important to produce compression stressin the second material layer 12 and produce tensile stress in the firstmaterial layer 11. Respective film thicknesses are preferably set to 1nm to 1000 nm as appropriate to adjust internal stress of the firstmaterial layer 11 and that of the second material layer 12. In addition,the internal stress of the first material layer 11 and that of thesecond material layer 12 may be adjusted by heat treatment or laserlight irradiation.

Also, for a simplification of a process, an example in which the firstmaterial layer 11 is formed in contact with the substrate 10 is shown inFIGS. 1A to 1D. An insulating layer or a metallic layer as a bufferlayer may be provided between the substrate 10 and the first materiallayer 11 to improve contact property to the substrate 10.

Next, the layer to be peeled 13 is formed on the second material layer12 (FIG. 1A). The layer to be peeled 13 is preferably a layer includingvarious elements (thin film diode, photoelectric conversion elementhaving a silicon PIN junction, and silicon resistor element) representedby a TFT. In addition, heat treatment can be performed as long as thesubstrate 10 can endure. Note that, even if the internal stress of thesecond material layer 12 is different from that of the first materiallayer 11 in the present invention, film peeling and the like are notcaused by heat treatment in a step of forming the layer to be peeled 13.

Next, contact property between the first material layer 11 and thesecond material layer 12 is partially reduced. Here, irradiation oflaser light 15 is conducted (FIG. 1B). For the laser light, a gas lasersuch as an excimer laser, a CO₂ laser, or an argon laser, a solid lasersuch as a glass laser, a ruby laser, an alexandrite laser, or a Ti:sapphire laser, a solid laser using crystal such as YAG, YVO₄, YLF, orYAlO₃ which is doped with Nd, Tm, or Ho, or a semiconductor laser ispreferably used. In addition, a laser oscillation type may be eithercontinuous oscillation or pulse oscillation. A laser beam may have alinear shape, a rectangular shape, a circular shape, or an ellipticalshape. A wavelength to be used may be a fundamental wave, the secondharmonic, or the third harmonic, and is preferably selected asappropriate by an operator. A scanning direction may be a longitudinaldirection, a transverse direction, or an oblique direction. Further,round trip scanning may be conducted.

Thus, it is important to prepare a portion where a peeling phenomenon iseasy to occur before peeling, that is, a lead. When preprocessing isperformed for selectively (partially) reducing the contact property,poor peeling is prevented and a yield is improved as well.

Next, peeling is conducted from a region to which the laser light isirradiated, thereby peeling the substrate 10 on which the first materiallayer 11 is provided toward a direction indicated by an arrow in FIG. 1Cby physical means (FIG. 1C).

The second material layer 12 has compression stress and the firstmaterial layer 11 has tensile stress. Thus, the substrate can be peeledby relatively small force (for example, by the hand of a person, by ablowing pressure of a gas blown from a nozzle, by ultrasound, or thelike). In addition, a portion having small contact property is partiallyformed by the above laser light processing. Thus, the substrate can bepeeled by smaller force.

Also, the example is shown under an assumption in which the layer to bepeeled 13 has a sufficient mechanical strength here. When the mechanicalstrength of the layer to be peeled 13 is insufficient, it is preferablethat the substrate is peeled after a support (not shown) for fixing thelayer to be peeled 13 is bonded thereto.

Thus, the layer to be peeled 13 formed on the second material layer 12can be separated from the substrate 10. A state obtained after peelingis shown in FIG. 1D.

Also, the separated layer to be peeled 13 may be bonded to a transferbody (not shown) after peeling.

Also, the present invention can be applied to various semiconductordevice manufacturing methods. Particularly, when a plastic substrate isused for the transfer body and the support, weight reduction isrealized.

When a liquid crystal display device is manufactured, it is preferablethat the support is used as a counter substrate and bonded to the layerto be peeled using a sealing member as a bonding layer. In this case,the element provided to the layer to be peeled has a pixel electrode. Aliquid crystal material is filled into a space between the pixelelectrode and the counter substrate. In addition, an order formanufacturing the liquid crystal display device is not particularlylimited. For example, the counter substrate as the support is bonded tothe layer to be peeled which is provided to the substrate, a liquidcrystal material is injected therebetween, and then the substrate ispeeled and the plastic substrate as the transfer body is bonded to thelayer to be peeled. Or, after the pixel electrode is formed, thesubstrate is peeled, the plastic substrate as a first transfer body isboned to the layer to be peeled, and then the counter substrate as asecond transfer body is bonded thereto.

Also, when a light emitting device represented by an EL light emittingdevice is manufactured, it is preferable that the support is used as asealing member. Thus, a light emitting element is completely shieldedfrom external so as to prevent entrance of a substance such as moistureor oxygen which promotes deterioration of an organic compound layer fromexternal. In addition, when the light emitting device represented by theEL light emitting device is manufactured, as in the case of the support,it is preferred to prevent entrance of a substance such as moisture oroxygen which promotes deterioration of an organic compound layer fromexternal. In addition, an order for manufacturing the light emittingdevice is not particularly limited. For example, after the lightemitting element is formed, a plastic substrate as the support is bondedto the layer to be peeled which is provided to a substrate, thesubstrate is peeled, and a plastic substrate as the transfer body isbonded to the layer to be peeled. Or, after the light emitting elementis formed, the substrate is peeled, a plastic substrate as a firsttransfer body is boned to the layer to be peeled, and then a plasticsubstrate as a second transfer body is bonded thereto.

Embodiment Mode 2

In this embodiment mode, an example in which a layer to be peeled ispeeled while a gas is blown onto an end surface thereof will be brieflydescribed using FIGS. 2A to 2C.

In FIG. 2A, reference numeral 20 denotes a substrate, 21 denotes a firstmaterial layer having tensile stress, 22 denotes a second material layerhaving compression stress, and 23 denotes a layer to be peeled. Notethat FIG. 2A is the same drawing as FIG. 1A and detailed descriptionsare omitted here.

After the state shown in FIG. 2A is obtained by the same order asEmbodiment Mode 1, as shown in FIG. 2B, while laser light 24 isirradiated to a portion, a gas is blown at a high pressure from a nozzle25 to an interface between the first material layer and the secondmaterial layer within an end surface of the substrate, therebyconducting peeling in a direction indicated by an arrow in FIG. 2B.

Here, a wind pressure is used as physical means. However, it is needlessto say that the physical means is not particularly limited. In addition,the example in which peeling by a wind pressure is conductedsimultaneously with the irradiation of the laser light 24 is shown here.The laser light irradiation may be initially performed to partiallyreduce the contact property between the first material layer 21 and thesecond material layer 22 and then peeling may be conducted by a windpressure.

Also, an inert gas such as, for example, a nitrogen gas or an argon gasis preferably used as the gas to be blown. The gas may be used under aroom temperature or heated to a high temperature.

Also, laser light 24 may be irradiated for scanning along a peelingdirection. In addition, the nozzle 25 may be moved.

The second material layer 22 has compression stress and the firstmaterial layer 21 has tensile stress. Thus, the layer to be peeled canbe peeled by a relatively small wind pressure. In addition, a portionhaving small contact property is partially formed by the above laserlight processing. Thus, the layer to be peeled can be peeled by asmaller wind pressure.

Also, the example is shown under an assumption in which the layer to bepeeled 23 has a sufficient mechanical strength is assumed is indicatedhere. When the mechanical strength of the layer to be peeled 23 isinsufficient, it is preferable that a support (not shown) for fixing thelayer to be peeled 23 is bonded thereto and then it is peeled.

Thus, the layer to be peeled 23 formed on the second material layer 22can be separated from the substrate 20. A state obtained after peelingis shown in FIG. 2C.

Also, the separated layer to be peeled 23 may be bonded to a transferbody (not shown) after peeling.

Also, the present invention can be applied to various semiconductordevice manufacturing methods. Particularly, when a plastic substrate isused for the transfer body and the support, weight reduction isrealized.

Embodiment Mode 3

In this embodiment mode, an example in which a pressure is applied to alayer to be peeled by a diamond pen before peeling to partially reducecontact property will be briefly described using FIGS. 3A to 3D.

In FIG. 3A, reference numeral 30 denotes a substrate, 31 denotes a firstmaterial layer having tensile stress, 32 denotes a second material layerhaving compression stress, and 33 denotes a layer to be peeled. Notethat FIG. 3A is the same drawing as FIG. 1A and detailed descriptionsare omitted here.

After the state shown in FIG. 3A is obtained by the same order asEmbodiment Mode 1, as shown in FIG. 3B, external force 35 is applied toa pen 34 to scratch the is layer to be peeled, thereby partiallyreducing the contact property between the first material layer 31 andthe second material layer 32. The diamond pen is used here. Preferably,a hard needle is vertically pressed and moved under a load.

Thus, it is important to prepare a portion where a peeling phenomenon iseasy to occur before peeling, that is, a lead. When preprocessing isperformed for selectively (partially) reducing the contact property,poor peeling is prevented and a yield is improved as well.

Next, peeling is conducted from a region to which the load is applied,thereby peeling the substrate 30 on which the first material layer 31 isprovided toward a direction indicated by an arrow in FIG. 3C by physicalmeans (FIG. 3C).

The second material layer 32 has compression stress and the firstmaterial layer 31 has tensile stress. Thus, the substrate can be peeledby relatively small force. In addition, a portion having small contactproperty is partially formed by the above laser light processing. Thus,the substrate can be peeled by smaller force.

Also, the example is shown under an assumption in which the layer to bepeeled 33 has a sufficient mechanical strength is assumed is indicatedhere. When the mechanical strength of the layer to be peeled 33 isinsufficient, it is preferable that the substrate is peeled after asupport (not shown) for fixing the layer to be peeled 33 is bondedthereto.

Thus, the layer to be peeled 33 formed on the second material layer 32can be separated from the substrate 30. A state obtained after peelingis shown in FIG. 3D.

Also, the separated layer to be peeled 33 may be bonded to a transferbody (not shown) after peeling.

Also, the present invention can be applied to various semiconductordevice manufacturing methods. Particularly, when a plastic substrate isused for the transfer is body and the support, weight reduction isrealized.

Also, the following test is conducted using the diamond pen. Here, a TiNfilm is used as the first material layer and an SiO₂ film is used as thesecond material layer.

In order to obtain a sample, a TiN film having a film thickness of 100nm is formed on a glass substrate by a sputtering method and then asilicon oxide film having a film thickness of 200 nm is formed by asputtering method.

Next, a silicon oxide layer is formed at a film thickness of 200 nm by asputtering method. With respect to a film formation condition for thesilicon oxide layer, an RF type sputtering apparatus and a silicon oxidetarget (30.5 cm in diameter) are used. In addition, a substratetemperature is set to 150° C., a film formation pressure is set to 0.4Pa, film formation power is set to 3 kW, and argon flow rate/oxygen flowrate=35 sccm/15 sccm.

Next, a base insulating layer is formed on the silicon oxide layer 33 bya plasma CVD method. With respect to the base insulating layer, asilicon oxynitride film (composition ratio: Si=32%, O=27%, N=24%, andH=17%) having a film thickness of 50 nm is formed at a film formationtemperature of 300° C. by a plasma CVD method using SiH₄, NH₃, and N₂Oas raw gases. The surface is washed with ozone water and then an oxidefilm produced on the surface is removed with diluted hydrofluoric acid (1/100 dilution). Then, a silicon oxynitride film (composition ratio:Si=32%, O=59%, N=7%, and H=2%) having a thickness of 100 nm is laminatedat a film formation temperature of 300° C. by a plasma CVD method usingSiH₄ and N₂O as raw gases. Further, a semiconductor layer having anamorphous structure (here, an amorphous silicon layer) with a thicknessof 54 nm is formed at a film formation temperature of 300° C. by aplasma CVD method using SiH₄ as a film formation gas without exposing itto air.

Next, a nickel acetate solution containing nickel at 10 ppm in weightconversion is applied onto the entire surface by spinner. A method ofspraying nickel elements over the entire surface by a sputtering methodmay be used instead of the application. Then, heat treatment isperformed for crystallization to form a semiconductor film having acrystalline structure (here, a polysilicon layer). Here, heat treatmentfor dehydrogenation (at 500° C. for 1 hour) is performed and then theheat treatment for crystallization (at 550° C. for 4 hours) is performedto obtain a silicon film having a crystalline structure. Note that acrystallization technique using nickel as a metallic element forpromoting crystallization of silicon is utilized here. Another knowncrystallization technique such as, for example, a solid phase method ora laser crystallization method may be used.

Next, a load line 41 shown in FIG. 4A is scratched by the diamond pen.The load line is arbitrary and set to be parallel to the end surface 40of the substrate within a region to be peeled 42. Here, a portion of thepolysilicon layer provided to the substrate, which is located in contactwith the end surface thereof, is peeled.

Next, a bonding tape is bonded to the region to be peeled (polysiliconlayer).

Next, tension is produced by the hand of a person in a directionindicated by an arrow (peeling direction) in FIG. 4B so as to separatethe bonding tape from the substrate. A state of the substrate which isobtained after peeling is shown in FIG. 4B and a state of the tape whichis obtained after peeling shown in FIG. 4C. A peeled region 43 can bevisibly observed in the tape.

For comparison, the bonding tape is boned without scratching by thediamond pen and then peeling is conducted. As a result, as shown in FIG.17A, even when the bonding tape is bonded to a region to be peeled 51, aregion 53 (FIG. 17B) left without being peeled is produced on thesubstrate. Thus, as shown in FIG. 17C, a peeled region 54 is partiallyproduced in the tape, thereby causing poor peeling.

The cause of poor peeling is considered as follows. That is, as comparedwith a central region of the substrate, a portion having a small filmthickness is easy to form in the outer edge thereof. If the filmthickness is small, a portion having high contact property to thesubstrate is formed and becomes hard to peel.

Thus, it is important to prepare a lead such that a peeling phenomenonis easy to occur before peeling. When preprocessing for selectively(partially) reducing the contact property is performed, the layer to bepeeled can be peeled over the entire surface from the substrate.

Here, scratching is conducted by the diamond pen before bonding of thebonding tape. Scratching may be conducted by the diamond pen afterbonding of the tape.

Also, the example is shown in which peeling is conducted using the firstmaterial layer (TiN layer) and the second material layer (SiO₂ layer)here. However, a peeling method is not particularly limited. Forexample, in a method of providing a separate layer made of amorphoussilicon (or polysilicon) and irradiating laser light thereto through asubstrate to release hydrogen contained in the amorphous silicon film,thereby producing gaps to separate the substrate from a layer to bepeeled, when preprocessing for selectively (partially) reducing thecontact property is performed on only the vicinity of the outer edge ofthe substrate before peeling, peeling can be conducted withoutinsufficient peeling.

Next, when TiN, W, WN, Ta, or TaN is used as a material of the firstmaterial layer, the second material layer (silicon oxide: 200 nm in filmthickness) is provided in contact with the first material layer. Then,the following test is conducted for checking whether or not the layer tobe peeled which is provided on the second material layer can be peeledfrom the substrate.

In order to obtain Sample 1, a TiN film having a film thickness of 100nm is formed on a glass substrate by a sputtering method and then asilicon oxide film having a film thickness of 200 nm is formed by thesputtering method. After the formation of the silicon oxide film,lamination and crystallization are performed as in the above test.

In order to obtain Sample 2, a W film having a film thickness of 50 nmis formed on a glass substrate by the sputtering method and then asilicon oxide film having a film thickness of 200 nm is formed by thesputtering method. After the formation of the silicon oxide film,lamination and crystallization are performed as in the above test.

In order to obtain Sample 3, a WN film having a film thickness of 50 nmis formed on a glass substrate by the sputtering method and then asilicon oxide film having a film thickness of 200 nm is formed by thesputtering method. After the formation of the silicon oxide film,lamination and crystallization are performed as in the above test.

In order to obtain Sample 4, a TiN film having a film thickness of 50 nmis formed on a glass substrate by the sputtering method and then asilicon oxide film having a film thickness of 200 nm is formed by thesputtering method. After the formation of the silicon oxide film,lamination and crystallization are performed as in the above test.

In order to obtain Sample 5, a Ta film having a film thickness of 50 nmis formed on a glass substrate by the sputtering method and then asilicon oxide film having a film thickness of 200 nm is formed by thesputtering method. After the formation of the silicon oxide film,lamination and crystallization are performed as in the above test.

In order to obtain Sample 6, a TaN film having a film thickness of 50 nmis formed on a glass substrate by the sputtering method and then asilicon oxide film having a film thickness of 200 nm is formed by thesputtering method. After the formation of the silicon oxide film,lamination and crystallization are performed as in the above test.

Thus, Samples 1 to 6 are obtained. With respect to each sample, aportion thereof is scratched by the diamond pen, then the bonding tapeis bonded to the layer to be peeled, and the test for checking whetheror not it is peeled is conducted. The result is indicated in Table 1.

TABLE 1 First material layer Second material layer (Lower layer) (Upperlayer) Tape test Sample 1 TiN (100 nm) Silicon oxide (200 nm) peeledSample 2 W (50 nm) Silicon oxide (200 nm) peeled Sample 3 WN (50 nm)Silicon oxide (200 nm) peeled Sample 4 TiN (50 nm) Silicon oxide (200nm) not peeled Sample 5 Ta (50 nm) Silicon oxide (200 nm) not peeledSample 6 TaN (50 nm) Silicon oxide (200 nm) not peeled

Also, with respect to the silicon oxide film, the TiN film, the W film,and the Ta film, each internal stress is measured before and after heattreatment (at 550° C. for 4 hours). The result is indicated in table 2.

TABLE 2 Internal stress value of film (dyne/cm²) After film formationAfter heat treatment Silicon oxide film −9.40E+08 −1.34E+09 −9.47E+08−1.26E+09 TiN film 3.90E+09 4.36E+09 3.95E+09 4.50E+09 W film −7.53E+098.96E+09 −7.40E+09 7.95E+09 Ta film 9.23E+09 −7.84E+09 5.16E+09−1.95E+10

Note that the measurement is conducted for the silicon oxide film formedat a film thickness of 400 nm on a silicon substrate by the sputteringmethod. In addition, the TiN film, the W film, and the Ta film each areformed at a film thickness of 400 nm on a glass substrate by thesputtering method and then each internal stress is measured. After that,the silicon oxide film is laminated as a cap film and heat treatment isperformed, and then the cap film is removed by etching and each internalstress is measured again. In addition, two Samples are produced for therespective films and the measurement is performed.

The W film has compression stress (about −7×10⁹ dyne/cm²) immediatelyafter the formation. However, it becomes a film having tensile stress(about 8×10⁹ dyne/cm² to 9×10⁹ dyne/cm²) by heat treatment. Thus, apreferable peeling state is obtained. With respect to the TiN film, thestress is almost the same before and after heat treatment and it hastensile stress (about 3.9×10⁹ dyne/cm² to 4.5×10⁹ dyne/cm²). When thefilm thickness is 50 nm or less, poor peeling is caused. In addition,with respect to the Ta film, it has tensile stress (about 5.1×10⁹dyne/cm² to 9.2×10⁹ dyne/cm²) immediately after the formation. However,the film becomes a film having compression stress (about −2×10⁹ dyne/cm²to −7.8×10⁹ dyne/cm²) by heat treatment. Thus, peeling is not producedin the tape test. In addition, with respect to the silicon film, thestress is almost the same before and after heat treatment and it hascompression stress (about −9.4×10⁸ dyne/cm² to −1.3×10⁹ dyne/cm²).

From these results, a peeling phenomenon is related to the contactproperty due to various factors. Particularly, it is greatly related tothe internal stress. When the second material layer having compressionstress is used and a film having tensile stress which is obtained byheat treatment is used as the first material layer, it can be read thatthe layer to be peeled can be peeled over the entire surface from thesubstrate. In addition, in the case where tensile stress is changed byheat treatment or laser light irradiation, it is desirable that amaterial in which a tensile stress value is increased as compared withthat before heat treatment or laser light irradiation is used for thefirst material layer.

Also, particularly when the first material layer or the second materiallayer is thin, processing for partially reducing the contact propertybefore peeling in the present invention is effective. This is because ifthe film thickness is small, a thickness distribution in a substrate atfilm formation is easy to vary and internal stress of a film, a filmquality, and the like are easy to change, thereby being hard to peel. Inorder to improve a throughput, it is preferable that the film thicknessof the first material layer or that of the second material layer isminimized.

The present invention made by the above constitution will be describedin more detail through the following embodiments.

Embodiment 1

An embodiment of the present invention is described with reference toFIGS. 5A to 7. Here, a method of simultaneously manufacturing a pixelportion and TFTs (n-channel TFTs and a p-channel TFT) of a drivercircuit provided in the periphery of the pixel portion on the samesubstrate is described in detail.

First, the first material layer 101, the second material layer 102, abase insulating film 103 are formed on a substrate 100 and asemiconductor film having a crystalline structure is obtained. Then, thesemiconductor film is etched to have a desired shape to formsemiconductor layers 104 to 108 separated from one another in an islandshape.

A glass substrate (#1737) is used as the substrate 100.

If materials using for the first material layer 101 having a tensilestress within a range of 1 to 1×10¹⁰ (dyne/cm²) directly before thepeeling process done later, the material is not particularly limited tospecific materials. A layer or lamination layer from the followingmaterial can be used for the first material layer 101; a metallicmaterial (Ti, Al, Ta, W, Mo, Cu, Cr, Nd, Fe, Ni, Co, Zr, Zn, Ru, Rh, Pd,Os, Ir, and Pt, etc.), semiconductor materials (for instance, Si and Ge,etc.), insulating materials or organic materials. Here, titanium nitridefilm having film thickness of 100 nm laminated by a sputtering method isused.

If materials used for the second material layer 102 having a compressivestress to within a range of −1 to −1×10¹⁰ (dyne/cm²) directly before thepeeling process done later, the material is not particularly limited tospecific materials. A layer or lamination layer from the following canbe used for the second material layer 102; a metallic material (Ti, Al,Ta, W, Mo, Cu, Cr, Nd, Fe, Ni, Co, Zr, Zn, Ru, Rh, Pd, Os, Ir, and Pt,etc.), semiconductor materials (for instance, Si and Ge, etc.),insulating materials or organic materials. Here, a single layer or alamination layer composed of oxide silicon material or oxide metalmaterial can be used. A silicon oxide film having film thickness of 200nm laminated by a sputtering method is used. The bonding force betweenthe first material layer 101 and the second material layer 102 is strongagainst heat treatment, so that the film peeling (also referred to aspeeling) or the like does not occur. However, it can be easily peeledoff on the inside of the second material layer or on the interface bythe physical means.

For the base insulating film 103, a silicon oxynitride film 103 a formedfrom SiH₄, NH₃, and N₂O as material gases (composition ratio: Si=32%,O=27%, N=24%, H=17%) is formed with a thickness of 50 nm (preferably 10to 200 nm) and at a film deposition temperature of 400° C. by usingplasma CVD. Then, after the surface is cleaned with ozone water, anoxide film on the surface is removed by means of dilute hydrofluoricacid (dilution with 1/100). Next, a silicon oxynitride film 103 b formedfrom SiH₄ and N₂O as material gases (composition ratio: Si=32%, O=59%,N=7%, H=2%) is formed thereon with a thickness of 100 nm (preferably 50to 200 nm) and at a film deposition temperature of 400° C. by usingplasma CVD to thereby form a lamination. Further, without exposure to anatmosphere, a semiconductor film having an amorphous structure (in thiscase, amorphous silicon film) is formed to have a thickness of 54 nm(preferably 25 to 80 nm) with SiH₄ as a film deposition gas and at afilm deposition temperature of 300° C. by using plasma CVD.

In this embodiment, the base film 103 is shown in a form of a two-layerstructure, but a single layer of the above-mentioned insulating film ora structure in which two or more layers thereof are laminated may beadopted. Further, there is no limitation on the material of thesemiconductor film. However, the semiconductor film may be preferablyformed of silicon or silicon germanium (Si_(X)Ge_(1-X) (X=0.0001 to0.02)) alloy by using a known means (sputtering, LPCVD, plasma CVD orthe like). Further, a plasma CVD apparatus may be a single wafer typeone or a batch type one. In addition, the base insulating film and thesemiconductor film may be continuously formed in the same film formationchamber without exposure to an atmosphere.

Subsequently, after the surface of the semiconductor film having anamorphous structure is cleaned, an extremely thin oxide film with athickness of about 2 nm is formed from ozone water on the surface. Then,in order to control a threshold value of a TFT, doping of a minuteamount of impurity element (boron or phosphorous) is performed. Here, anion doping method is used in which diborane (B₂H₆) is plasma-excitedwithout mass-separation, and boron is added to the amorphous siliconfilm under the doping conditions: an acceleration voltage of 15 kV; agas flow rate of diborane diluted to 1% with hydrogen of 30 sccm; and adosage of 2×10¹²/cm².

Then, a nickel acetate salt solution containing nickel of 10 ppm inweight is applied using a spinner. Instead of the application, a methodof spraying nickel elements to the entire surface by sputtering may alsobe used.

Then, heat treatment is conducted to perform crystallization, therebyforming a semiconductor film having a crystalline structure. A heattreatment using an electric furnace or irradiation of strong light maybe conducted for this heat treatment. In case of the heat treatmentusing an electric furnace, it may be conducted at 500 to 650° C. for 4to 24 hours. Here, after the heat treatment (500° C. for 1 hour) fordehydrogenation is conducted, the heat treatment (550° C. for 4 hours)for crystallization is conducted, thereby obtaining a silicon filmhaving a crystalline structure. Note that, although crystallization isperformed by using the heat treatment using a furnace, crystallizationmay be performed by means of a lamp annealing apparatus. Also note that,although a crystallization technique using nickel as a metal elementthat promotes crystallization of silicon is used here, other knowncrystallization techniques, for example, a solid-phase growth method anda laser crystallization method, may be used.

Next, after the oxide film on the surface of the silicon film having acrystalline structure is removed by dilute hydrofluoric acid or thelike, irradiation of first laser light (XeCl: wavelength of 308 nm) forraising a crystallization rate and repairing defects remaining incrystal grains is performed in an atmosphere or in an oxygen atmosphere.Excimer laser light with a wavelength of 400 nm or less, or secondharmonic wave or third harmonic wave of a YAG laser is used for thelaser light. In this case, pulse laser light with a repetition frequencyof approximately 10 to 1000 Hz is used, the pulse laser light iscondensed to 100 to 500 mJ/cm² by an optical system, and irradiation isperformed with an overlap ratio of 90 to 95%, whereby the silicon filmsurface may be scanned. Here, the irradiation of the first laser lightis performed in an atmosphere with a repetition frequency of 30 Hz andenergy density of 393 mJ/cm². Note that an oxide film is formed on thesurface by the first laser light irradiation since the irradiation isconducted in an atmosphere or in an oxygen atmosphere. Also note that,although, an example of using a pulse laser is shown here, a continuousoscillation laser may also be used. When an amorphous semiconductor filmis crystallized, it is preferable to use a solid laser which canoscillate continuously and to apply the second harmonic wave to thefourth harmonic wave in order to obtain a large particle size crystal.Typically, it only has to apply the second harmonic wave (532 nm) andthe third harmonic wave (355 nm) of the Nd:YVO₄ laser (basic wave 1064nm). When a continuous oscillation laser is used, the laser lightinjected from a continuous oscillation YVO₄ laser of output 10 W isconverted into a harmonic wave is with a nonlinear optical element.Moreover, there is a method of injecting a harmonic wave by putting theYVO₄ crystal and a nonlinear optical element into the resonator.Preferably, the laser light is formed into a rectangular shape or anelliptic shape on the radiation surface, and the laser light is radiatedto the processed substrate. The energy density at this time is necessaryabout 0.01 to 100 MW/cm² (Desirability is 0.1 to 10 MW/cm²). Thesemiconductor film is moved relatively at 10 to 2000 cm/s with respectto the laser light, and the laser light can be radiated.

Next, after the oxide film formed by the first laser light irradiationis removed by dilute hydrofluoric acid, the second laser lightirradiation is performed in a nitrogen atmosphere or in a vacuum,thereby the semiconductor film surface is leveled. Excimer laser lightwith a wavelength of 400 nm or less, or second harmonic wave or thirdharmonic wave of a YAG laser is used as the laser light (the secondlaser light). The energy density of the second laser light is madelarger than that of the first laser light, preferably made larger by 30to 60 mJ/cm². Here, the second laser light irradiation is performed witha repetition frequency of 30 Hz and energy density of 453 mJ/cm² tothereby set a P-V value (Peak to Valley, the difference between themaximum value and the minimum value in height) of unevenness in thesemiconductor film surface to 50 nm or less. Here, the P-V value ofunevenness may be obtained by AFM (atomic force microscope).

Further, although the second laser light irradiation is conducted overthe surface in this embodiment, a step of selectively performingirradiation at least on a pixel portion may be adopted since thereduction of an off current particularly has an effect on a TFT of thepixel portion.

Next, the surface is processed with ozone water for 120 seconds, therebyforming a barrier layer comprised of an oxide film with a thickness of 1to 5 nm in total.

Then, an amorphous silicon film containing an argon element, whichbecomes a gettering site, is formed on the barrier layer to have athickness of 150 nm by sputtering. The film deposition conditions withsputtering in this embodiment are: a film deposition pressure of 0.3 Pa;a gas (Ar) flow rate of 50 sccm; a film deposition power of 3 kW; and asubstrate temperature of 150° C. Note that under the above conditions,the atomic concentration of the argon element contained in the amorphoussilicon film is 3×10²⁰/cm³ to 6×10²⁰/cm³, and the atomic concentrationof oxygen is 1×10¹⁹/cm³ to 3×10¹⁹/cm³. Thereafter, heat treatment at650° C. for 3 minutes is conducted using the lamp annealing apparatus toperform gettering.

Subsequently, the amorphous silicon film containing the argon element,which is the gettering site, is selectively removed with the barrierlayer as an etching stopper, and then, the barrier layer is selectivelyremoved by dilute hydrofluoric acid. Note that there is a tendency thatnickel is likely to move to a region with a high oxygen concentration ingettering, and thus, it is desirable that the barrier layer comprised ofthe oxide film is removed after gettering.

Then, after a thin oxide film is formed from ozone water on the surfaceof the obtained silicon film having a crystalline structure (alsoreferred to as polysilicon film), a mask made of resist is formed, andan etching process is conducted thereto to obtain a desired shape,thereby forming the island-like semiconductor layers 104 to 108separated from one another. After the formation of the semiconductorlayers, the mask made of resist is removed.

Then, the oxide film is removed with the etchant containing hydrofluoricacid, and at the same time, the surface of the silicon film is cleaned.Thereafter, an insulating film containing silicon as its mainconstituent, which becomes a gate insulating film 109, is formed. Inthis embodiment, a silicon oxynitride film (composition ratio: Si=32%,O=59%, N=7%, H=2%) is formed with a thickness of 115 nm by plasma CVD.

Next, as shown in FIG. 5A, on the gate insulating film 109, a firstconductive film 110 a with a thickness of 20 to 100 nm and a secondconductive film 110 b with a thickness of 100 to 400 nm are formed inlamination. In this embodiment, a 50 nm thick tantalum nitride film anda 370 nm thick tungsten film are sequentially laminated on the gateinsulating film 109.

As a conductive material for forming the first conductive film and thesecond conductive film, an element selected from the group consisting ofTa, W, Ti, Mo, Al and Cu, or an alloy material or compound materialcontaining the above element as its main constituent is employed.Further, a semiconductor film typified by a polycrystalline silicon filmdoped with an impurity element such as phosphorous, or an AgPdCu alloymay be used as the first conductive film and the second conductive film.Further, the present invention is not limited to a two-layer structure.For example, a three-layer structure may be adopted in which a 50 nmthick tungsten film, an alloy film of aluminum and silicon (Al—Si) witha thickness of 500 nm, and a 30 nm thick titanium nitride film aresequentially laminated. Moreover, in case of a three-layer structure,tungsten nitride may be used in place of tungsten of the firstconductive film, an alloy film of aluminum and titanium (Al—Ti) may beused in place of the alloy film of aluminum and silicon (Al—Si) of thesecond conductive film, and a titanium film may be used in place of thetitanium nitride film of the third conductive film. In addition, asingle layer structure may also be adopted.

Next, as shown in FIG. 5B, masks 112 to 117 are formed by a lightexposure step, and a first etching process for forming gate electrodesand wirings is performed. The first etching process is performed withfirst and second etching conditions. An ICP (Inductively Coupled Plasma)etching method may be preferably used for the etching process. The ICPetching method is used, and the etching conditions (an electric energyapplied to a coil-shape electrode, an electric energy applied to anelectrode on a substrate side, a temperature of the electrode on thesubstrate side, and the like) are appropriately adjusted, whereby a filmcan be etched to have a desired taper shape. Note that chlorine-basedgases typified by Cl₂, BCl₃, SiCl₄, CCl₄ or the like, fluorine-basedgases typified by CF₄, SF₆, NF₃, or the like and O₂ can be appropriatelyused as etching gases.

In this embodiment, RF (13.56 MHZ) power of 150 W is applied also to thesubstrate (sample stage) to substantially apply a negative self-biasvoltage. It should be noted that the size of the electrode area on theside of the substrate is 12.5 cm×12.5 cm and the size of the coil typeelectrode area (here, quartz disk on which the coil is provided) is adisk having a diameter of 25 cm. With the first etching conditions, a Wfilm is etched to form an end portion of the first conductive layer intoa tapered shape. Under the first etching conditions, an etching rate toW is 200.39 nm/min, an etching rate to TaN is 80.32 nm/min, and aselection ratio of W to TaN is about 2.5. Further, with the firstetching conditions, a taper angle of W is approximately 26°. Thereafter,the first etching conditions are changed to the second etchingconditions without removing the masks 112 to 117 made of resist. CF₄ andCl₂ are used as etching gases, the flow rate of the gases is set to30/30 sccm, and RF (13.56 MHZ) power of 500 W is applied to a coil-shapeelectrode with a pressure of 1 Pa to generate plasma, thereby performingetching for about 30 seconds. RF (13.56 MHZ) power of 20 W is alsoapplied to the substrate side (sample stage) to substantially apply anegative self-bias voltage. Under the second etching conditions in whichCF₄ and Cl₂ are mixed, both the W film and the TaN film are etched atthe same level. With the second etching conditions, an etching rate to Wis 58.97 nm/min, and an etching rate to TaN is 66.43 nm/min. Note thatan etching time may be increased by 10 to 20% in order to conductetching without remaining residue on the gate insulating film.

In the first etching process as described above, the shape of the maskmade of resist is made appropriate, whereby the end portion of the firstconductive layer and the end portion of the second conductive layer eachhave a tapered shape due to the effect of the bias voltage applied tothe substrate side. The angle of the tapered portion is sufficiently setto 15 to 45°.

Thus, first shape conductive layers 119 to 123 composed of the firstconductive layer and the second conductive layer (first conductivelayers 119 a to 123 a and second conductive layers 119 b to 123 b) areformed by the first etching process. The insulating film 109 thatbecomes the gate insulating film is etched by approximately 10 to 20 nm,and becomes a gate insulating film 118 in which regions which are notcovered by the first shape conductive layers 119 to 123 are thinned.

Next, a second etching process is conducted without removing the masksmade of resist. Here, SF₆, Cl₂ and O₂ are used as etching gases, theflow rate of the gases is set to 24/12/24 (sccm), and RF (13.56 MHZ)power of 700 W is applied to a coil-shape electrode with a pressure of1.3 Pa to generate plasma, thereby performing etching for 25 seconds. RF(13.56 MHZ) power of 10 W is also applied to the substrate side (samplestage) to substantially apply a negative self-bias voltage. In thesecond etching process, an etching rate to W is 227.3 nm/min, an etchingrate to TaN is 32.1 nm/min, a selection ratio of W to TaN is 7.1, anetching rate to SiON that is the insulating film 118 is 33.7 nm/min, anda selection ratio of W to SiON is 6.83. In the case where SF₆ is used asthe etching gas, the selection ratio with respect to the insulating film118 is high as described above. Thus, reduction in the film thicknesscan be suppressed. In this embodiment, the film thickness of theinsulating film 118 is reduced by only about 8 nm.

By the second etching process, the taper angle of W becomes 70°. By thesecond etching process, second conductive layers 126 b to 131 b areformed. On the other hand, the first conductive layers are hardly etchedto become first conductive layers 126 a to 131 a. Note that the firstconductive layers 126 a to 131 a have substantially the same size as thefirst conductive layers 119 a to 124 a. In actuality, the width of thefirst conductive layer may be reduced by approximately 0.3 μm, namely,approximately 0.6 μm in the total line width in comparison with beforethe second etching process. However, there is almost no change in sizeof the first conductive layer.

Further, in the case where, instead of the two-layer structure, thethree-layer structure is adopted in which a 50 nm thick tungsten film,an alloy film of aluminum and silicon (Al—Si) with a thickness of 500nm, and a 30 nm thick titanium nitride film are sequentially laminated,under the first etching conditions of the first etching process inwhich: BCl₃, Cl₂ and O₂ are used as material gases; the flow rate of thegases is set to 65/10/5 (sccm); RF (13.56 MHZ) power of 300 W is appliedto the substrate side (sample stage); and RF (13.56 MHZ) power of 450 Wis applied to a coil-shape electrode with a pressure of 1.2 Pa togenerate plasma, etching is performed for 117 seconds. As to the secondetching conditions of the first etching process, CF₄, Cl₂ and O₂ areused, the flow rate of the gases is set to 25/25/10 sccm, RF (13.56 MHZ)power of 20 W is also applied to the substrate side (sample stage); andRF (13.56 MHZ) power of 500 W is applied to a coil-shape electrode witha pressure of 1 Pa to generate plasma. With the above conditions, it issufficient that etching is performed for about 30 seconds. In the secondetching process, BCl₃ and Cl₂ are used, the flow rate of the gases areset to 20/60 sccm, RF (13.56 MHZ) power of 100 W is applied to thesubstrate side (sample stage), and RF (13.56 MHZ) power of 600 W isapplied to a coil-shape electrode with a pressure of 1.2 Pa to generateplasma, thereby performing etching.

Next, the masks made of resist are removed, and then, a first dopingprocess is conducted to obtain the state of FIG. 5D. The doping processmay be conducted by ion doping or ion implantation. Ion doping isconducted with the conditions of a dosage of 1.5×10¹⁴ atoms/cm² and anaccelerating voltage of 60 to 100 keV. As an impurity element impartingn-type conductivity, phosphorous (P) or arsenic (As) is typically used.In this case, first conductive layers and second conductive layers 126to 130 become masks against the impurity element imparting n-typeconductivity, and first impurity regions 132 to 136 are formed in aself-aligning manner. The impurity element imparting n-type conductivityis added to the first impurity regions 132 to 136 in a concentrationrange of 1×10¹⁶ to 1×10¹⁷/cm³. Here, the region having the sameconcentration range as the first impurity region is also called an nregion.

Note that although the first doping process is performed after theremoval of the masks made of resist in this embodiment, the first dopingprocess may be performed without removing the masks made of resist.

Subsequently, as shown in FIG. 6A, masks 137 to 139 made of resist areformed, and a second doping process is conducted. The mask 137 is a maskfor protecting a channel forming region and a periphery thereof of asemiconductor layer forming a p-channel TFT of a driver circuit, themask 138 is a mask for protecting a channel forming region and aperiphery thereof of a semiconductor layer forming one of n-channel TFTsof the driver circuit, and the mask 139 is a mask for protecting achannel forming region, a periphery thereof, and a storage capacitor ofa semiconductor layer forming a TFT of a pixel portion.

With the ion doping conditions in the second doping process: a dosage of1.5×10¹⁵ atoms/cm²; and an accelerating voltage of 60 to 100 keV,phosphorous (P) is doped. Here, impurity regions are formed in therespective semiconductor layers in a self-aligning manner with thesecond conductive layers 126 b to 128 b as masks. Of course, phosphorousis not added to the regions covered by the masks 137 to 139. Thus,second impurity regions 140 to 142 and a third impurity region 144 areformed. The impurity element imparting n-type conductivity is added tothe second impurity regions 140 to 142 in a concentration range of1×10²⁰ to 1×10²¹/cm³. Here, the region having the same concentrationrange as the second impurity region is also called an n⁺ region.

Further, the third impurity region is formed at a lower concentrationthan that in the second impurity region by the first conductive layer,and is added with the impurity element imparting n-type conductivity ina concentration range of 1×10¹⁸ to 1×10¹⁹/cm³. Note that since doping isconducted by passing the portion of the first conductive layer having atapered shape, the third impurity region has a concentration gradient inwhich an impurity concentration increases toward the end portion of thetapered portion. Here, the region having the same concentration range asthe third impurity region is also called an ⁻ region. Furthermore, theregions covered by the masks 138 and 139 are not added with the impurityelement in the second doping process, and become first impurity regions145, 146 and 147.

Next, after the masks 137 to 139 made of resist are removed, masks 148to 150 made of resist are newly formed, and a third doping process isconducted as shown in FIG. 6B.

In the driver circuit, by the third doping process as described above,fourth impurity regions 151, 152 and fifth impurity regions 153, 154 areformed in which an impurity element imparting p-type conductivity isadded to the semiconductor layer forming the p-channel and to thesemiconductor layer forming the storage capacitor.

Further, the impurity element imparting p-type conductivity is added tothe fourth impurity regions 151 and 152 in a concentration range of1×10²⁰ to 1×10²¹/cm³. Note that, in the fourth impurity regions 151,152, phosphorous (P) has been added in the preceding step (n region),but the impurity element imparting p-type conductivity is added at aconcentration that is 1.5 to 3 times as high as that of phosphorous.Thus, the fourth impurity regions 151, 152 have a p-type conductivity.Here, the region having the same concentration range as the fourthimpurity region is also called a p⁺ region.

Further, fifth impurity regions 153 and 154 are formed in regionsoverlapping the tapered portion of the second conductive layer 127 a,and are added with the impurity element imparting p-type conductivity ina concentration range of 1×10¹⁸ to 1×10²⁰/cm³. Here, the region havingthe same concentration range as the fifth impurity region is also calleda p⁻ region.

Through the above-described steps, the impurity regions having n-type orp-type conductivity are formed in the respective semiconductor layers.The conductive layers 126 to 129 become gate electrodes of a TFT.Further, the conductive layer 130 becomes one of electrodes, which formsthe storage capacitor in the pixel portion. Moreover, the conductivelayer 131 forms a source wiring in the pixel portion.

Next, an insulating film (not shown) that covers substantially theentire surface is formed. In this embodiment, a 50 nm thick siliconoxide film is formed by plasma CVD. Of course, the insulating film isnot limited to a silicon oxide film, and other insulating filmscontaining silicon may be used in a single layer or a laminationstructure.

Then, a step of activating the impurity element added to the respectivesemiconductor layers is conducted. In this activation step, a rapidthermal annealing (RTA) method using a lamp light source, a method ofirradiating light emitted from a YAG laser or excimer laser from theback surface, heat treatment using a furnace, or a combination thereofis employed.

Further, although an example in which the insulating film is formedbefore the activation is shown in this embodiment, a step of forming theinsulating film may be conducted after the activation is conducted.

Next, a first interlayer insulating film 155 is formed of a siliconnitride film, and heat treatment (300 to 550° C. for 1 to 12 hours) isperformed, thereby conducting a step of hydrogenating the semiconductorlayers. (FIG. 6C) This step is a step of terminating dangling bonds ofthe semiconductor layers by hydrogen contained in the first interlayerinsulating film 155. The semiconductor layers can be hydrogenatedirrespective of the existence of an insulating film (not shown) formedof a silicon oxide film. Incidentally, in this embodiment, a materialcontaining aluminum as its main constituent is used for the secondconductive layer, and thus, it is important to apply the heat treatmentcondition that the second conductive layer can withstand in the step ofhydrogenation. As another means for hydrogenation, plasma hydrogenation(using hydrogen excited by plasma) may be conducted.

Next, a second interlayer insulating film 156 is formed from an organicinsulating material on the first interlayer insulating film 155. In thisembodiment, an acrylic resin film with a thickness of 1.6 μm is formed.Then, a contact hole that reaches the source wiring 131, contact holesthat respectively reach the conductive layers 129 and 130, and contactholes that reach the respective impurity regions are formed. In thisembodiment, plurality of etching processes are sequentially performed.In this embodiment, the second interlayer insulting film is etched withthe first interlayer insulating film as the etching stopper, the firstinterlayer insulating film is etched with the insulating film (notshown) as the etching stopper, and then, the insulating film (not shown)is etched.

Thereafter, wirings and pixel electrode are formed by using Al, Ti, Mo,W and the like. As the material of the electrodes and pixel electrode,it is desirable to use a material excellent in reflecting property, suchas a film containing Al or Ag as its main constituent or a laminationfilm of the above film. Thus, source electrodes or drain electrodes 157to 162, a gate wiring 164, a connection wiring 163, and a pixelelectrode 165 are formed.

As described above, a driver circuit 206 having an n-channel TFT 201, ap-channel TFT 202, and an n-channel TFT 203 and a pixel portion 207having a pixel TFT 204 comprised of an n-channel TFT and a storagecapacitor 205 can be formed on the same substrate. (FIG. 7) In thisspecification, the above substrate is called an active matrix substratefor the sake of convenience.

In the pixel portion 207, the pixel TFT 204 (n-channel TFT) has achannel forming region 169, the first impurity region (n⁻ region) 147formed outside the conductive layer 129 forming the gate electrode, andthe second impurity region (n⁺ region) 142 and 171 functioning as asource region or a drain region. Further, in the semiconductor layerfunctioning as one of the electrodes of the storage capacitor 205, thefourth impurity region 152 and the fifth impurity region 154 are formed.The storage capacitor 205 is constituted of the second electrode 130 andthe semiconductor is layers 152, 154, and 170 with the insulating film(the same film as the gate insulating film) 118 as dielectric.

Further, in the driver circuit 206, the n-channel TFT 201 (firstn-channel TFT) has a channel forming region 166, the third impurityregion (n⁻ region) 144 that overlaps a part of the conductive layer 126forming the gate electrode through the insulating film, and the secondimpurity region (n⁺ region) 140 functioning as a source region or adrain region.

Further, in the driver circuit 206, the p-channel TFT 202 has a channelforming region 167, the fifth impurity region (p⁻ region) 153 thatoverlaps a part of the conductive layer 127 forming the gate electrodethrough the insulating film, and the fourth impurity region (p⁺ region)151 functioning as a source region or a drain region.

Furthermore, in the driver circuit 206, the n-channel TFT 203 (secondre-channel TFT) has a channel forming region 168, the first impurityregion (n⁻ region) 146 outside the conductive layer 128 forming the gateelectrode, and the second impurity region (n⁺ region) 141 functioning asa source region or a drain region.

The above TFTs 201 to 203 are appropriately combined to form a shiftregister circuit, a buffer circuit, a level shifter circuit, a latchcircuit and the like, thereby forming the driver circuit 206. Forexample, in the case where a CMOS circuit is formed, the n-channel TFT201 and the p-channel TFT 202 may be complementarily connected to eachother.

In particular, the structure of the n-channel TFT 203 is appropriate forthe buffer circuit having a high driving voltage with the purpose ofpreventing deterioration due to a hot carrier effect.

Moreover, the structure of the n-channel TFT 201, which is a GOLDstructure, is appropriate for the circuit in which the reliability takestop priority.

From the above, the reliability can be improved by improving theflatness of the semiconductor film surface. Thus, in the TFT having theGOLD structure, sufficient reliability can be obtained even if the areaof the impurity region that overlaps the gate electrode through the gateinsulating film is reduced. Specifically, in the TFT having the GOLDstructure, sufficient reliability can be obtained even if the size ofthe portion that becomes the tapered portion of the gate electrode isreduced.

In the TFT with the GOLD structure, a parasitic capacitance increaseswhen the gate insulating film is thinned. However, the size of thetapered portion of the gate electrode (first conductive layer) isreduced to reduce the parasitic capacitance, whereby the TFT becomes toenable high-speed operation with improved f-characteristic (frequencycharacteristic) and to have sufficient reliability.

Note that, in the pixel TFT of the pixel portion 207 as well, the secondlaser light irradiation enables the reduction in off current and thereduction in fluctuation.

Further, an example of manufacturing the active matrix substrate forforming a reflection type display device is shown in this embodiment.However, if the pixel electrode is formed of a transparent conductivefilm, a transmission type display device can be formed although thenumber of photomasks is increased by one.

Moreover, in this embodiment, a glass substrate was used, but it is notparticularly limited. A quartz substrate, a semiconductor substrate, aceramic substrate, and a metal substrate can be used.

Moreover, after the state of FIG. 7 is obtained, if the layer(peeled-off layer) containing a TFT provided on the second materiallayer 102 has a sufficient mechanical strength, the substrate 100 may bepeeled off. The substrate 100 can be peeled off by comparatively smallpower (for instance, a man's hand, a wind pressure insufflated from anozzle, a supersonic and the like) because the second material layer 102has the compressive stress, and the first material layer 101 has thetensile stress. In this embodiment, since the mechanical strength of thepeeled-off layer is not sufficient, it is preferred that the peeled-offlayer is peeled off after the supporting body (not shown) for fixing thepeeled-off layer.

Embodiment 2

In this embodiment, steps of peeling the substrate 100 from the activematrix substrate produced in Embodiment 1 and then bonding it to aplastic substrate to manufacture an active matrix liquid crystal displaydevice will be described below. FIGS. 8A to 8D are used for thedescription.

In FIG. 8A, reference numeral 400 denotes a substrate, 401 denotes afirst material layer, 402 denotes a second material layer, 403 denotes abase insulating layer, 404 a denotes an element of a driver circuit 413,404 b denotes an element of a pixel portion 414, and 405 denotes a pixelelectrode. Here, the element indicates a semiconductor element(typically, a TFT), an MIM element, or the like which is used as answitching element of a pixel in the active matrix liquid crystal displaydevice. An active matrix substrate of FIG. 8A is shown by simplifyingthe active matrix substrate of FIG. 7. The substrate 100 in FIG. 7corresponds to the substrate 400 in FIG. 8A. In the same manner,reference numeral 401 in FIG. 8A corresponds to 101 in FIG. 7, 402corresponds to 102, 403 corresponds to 103, 404 a corresponds to 201 and202, 404 b corresponds to 204, and 405 corresponds to 165.

First, after the active matrix substrate shown in FIG. 7 is obtained inaccordance with Embodiment 1, an alignment film 406 a is formed on theactive matrix substrate and rubbing processing is performed. Note that,in this embodiment, an organic resin film such as an acrylic resin filmis patterned form column-shaped spacers (not shown) for keeping asubstrate interval constant at predetermined positions before theformation of the alignment film. Instead of the column-shaped spacers,spherical spacers may be sprayed on the entire surface of the substrate.

Next, a counter substrate is prepared as a support 407. A color filter(not shown) in which a colored layer and a light shielding layer arelocated corresponding to each pixel is provided to the countersubstrate. A glass substrate may be used as the counter electrode. Here,a plastic substrate is used for weight reduction. In addition, a lightshielding layer is provided to a region of the driver circuit. Aplanarizing film (not shown) which covers the color filter and the lightshielding layers is provided. Then, a counter electrode 408 made from atransparent conductive film is formed on the planarizing film in thepixel portion. An alignment film 406 b is formed on the entire surfaceof the counter substrate and rubbing processing is performed.

Then, the active matrix substrate 400 on which the pixel portion and thedriver circuit are formed and the support 407 are bonded to each otherthrough a sealing member serving as a bonding layer 409. A filler ismixed into the sealing member. Thus, the two substrates are bonded toeach other with the filler and the column-shaped spacers at apredetermined interval. After that, a liquid crystal material 410 isinjected between both substrates and complete sealing is conducted by asealing agent (not shown) (FIG. 8B). A known liquid crystal material maybe used as the liquid crystal material 410.

Next, any one of processings shown in Embodiment Modes 1 to 3(processing for partially reducing the contact property) is performed.Here, an example of laser light irradiation will be described usingFIGS. 9A to 9C. FIG. 9A is a schematic perspective view of the activematrix substrate and shows a substrate 50 to which a layer to be peeled51 a is provided. The substrate 400 shown in FIG. 8A corresponds to thesubstrate 50 shown in FIG. 9A and both substrates are the same. Here,the layer to be peeled 51 a includes the TFTs, the liquid crystal, andthe counter electrode. In order to partially reduce the contactproperty, laser light is irradiated from the front surface side or therear surface side along one end surface of the substrate to provide alaser light irradiation region 56. Then, the substrate 50 is peeled fromthe laser light irradiation region 56 side by physical means. FIG. 9B isa perspective view showing the progress of peeling. The plasticsubstrate is used as the counter electrode. Thus, a state that the layerto be peeled 51 b is bended is shown in FIG. 9B. However, there is apossibility that a crack is caused in the layer to be peeled 51 b.Accordingly, it is desirable that the layer to be peeled is not bendedif possible. Thus, as shown in FIG. 9C, it is desirable that all channellength directions of thin film transistors are identical with each otherso that an angle formed by a channel length direction of each ofsemiconductor layers 52 a, 53 a, and 54 a serving as active layers ofTFTs and a bending direction (peeling direction) 55 becomes 90°. Inother words, it is desirable that a channel width direction of each ofthe TFTs is aligned with the bending direction (peeling direction) 55.Thus, even if the layer to be peeled having the element is bended, theinfluence on element characteristics can be minimized. Note that FIG. 9Cshows the progress of peeling as in FIG. 9B. In addition, forsimplification, the substrate is not shown and only semiconductor layersof TFTs in a pixel portion 52, a driver circuit (X-direction) 53, and adriver circuit (Y-direction) 54 which are provided to the layer to bepeeled 51 b are shown. In FIG. 9C, reference numerals 52 b, 53 b, and 54b denote channel length directions.

FIG. 8C shows a state which is obtained after peeling. The secondmaterial layer 402 has compression stress and the first material layer401 has tensile stress. Thus, the layer to be peeled can be peeled byrelatively small force (for example, by the hand of a person, by ablowing pressure of a gas blown from a nozzle, by ultrasound, or thelike).

Next, the peeled layer is bonded to a transfer body 412 through abonding layer 411 made of an epoxy resin or the like. In thisembodiment, a plastic film substrate is used as the transfer body 412for weight reduction.

Thus, a flexible active matrix liquid crystal display device iscompleted. If necessary, the flexible substrate 412 or the countersubstrate is divided in predetermined shapes. Further, a polarizingplate (not shown) and the like are provided as appropriate by a knowntechnique. Then, an FPC (not shown) is bonded by a known technique.

Embodiment 3

The structure of the liquid crystal module obtained by Embodiment 2 isdescribed with reference to the top view in FIG. 10. A substrate 412 inEmbodiment 2 corresponds to a substrate 301.

A pixel portion 304 is placed in the center of a substrate 301. A sourcesignal line driving circuit 302 for driving source signal lines ispositioned above the pixel portion 304. Gate signal line drivingcircuits 303 for driving gate signal lines are placed to the left andright of the pixel portion 304. Although the gate signal line drivingcircuits 303 are symmetrical with respect to the pixel portion in thisembodiment, the liquid crystal module may have only one gate signal linedriving circuit on one side of the pixel portion. A designer can choosethe arrangement that suits better in consideration of the substrate sizeor the like of the liquid crystal module. However, the symmetricalarrangement of the gate signal line driving circuits shown in FIG. 10 ispreferred in terms of circuit operation reliability, driving efficiency,and the like.

Signals are inputted to the driving circuits from flexible printedcircuits (FPC) 305. The FPCs 305 are press-fit through an anisotropicconductive film or the like after opening contact holes in theinterlayer insulating film and a resin film and forming a connectionelectrode so as to reach the wiring lines arranged in given places ofthe substrate 301. The connection electrode is formed from ITO in thisembodiment.

A sealing agent 307 is applied to the substrate along its perimetersurrounding the driving circuits and the pixel portion and then anopposite substrate 306 is bonded by the sealing agent 307 while a spacerformed in advance on the film substrate keeps the distance between thesubstrate 301 and the opposite substrate 306. A liquid crystal elementis injected through an area of the substrate that is not coated with thesealing agent 307. The substrates are then sealed by an encapsulant 308.The device, containing all of these, shown FIG. 10 is called the liquidcrystal module.

Although all of the driving circuits are formed on the film substrate inthis embodiment shown here, several ICs may be used for some of thedriving circuits.

This embodiment can be freely combined with Embodiment 1.

Embodiment 4

In this embodiment, an example of manufacturing a light emitting displaydevice including an EL (electro luminescence) element formed on aplastic substrate is shown in FIGS. 11A to 11D.

In FIG. 11A, reference numeral 600 denotes a substrate, 601 denotes afirst material layer, 602 denotes a second material layer, 603 denotes abase insulating layer, 604 a denotes an element of a driver circuit 611,604 b and 604 c denote elements of a pixel portion 612, and 605 denotesan OLED (organic light emitting device). Here, the element indicates asemiconductor element (typically, a TFT), an MIM element, an OLED, orthe like which is used as an switching element of a pixel in the case ofan active matrix light emitting device. An interlayer insulating film606 is formed to cover these elements. It is desirable that the surfaceof the interlayer insulating film 606 obtained after the formation isflatter. Note that the interlayer insulating film 606 is not necessarilyprovided.

Note that the layers 601 to 603 provided on the substrate 600 arepreferably formed in accordance with Embodiment 1.

These elements (including 604 a, 604 b, and 604 c) are preferablymanufactured in accordance with the n-channel TFT 201 and the p-channelTFT 202 in the above Embodiment 1.

The OLED 605 has a layer including an organic compound (organic lightemitting material) in which luminescence (electroluminescence) isproduced by applying an electric field thereto (hereinafter referred toas an organic light emitting layer), an anode layer, and a cathodelayer. As the luminescence in the organic compound, there are lightemission (fluorescence) produced when it is returned from a singletexcitation state to a ground state and light emission (phosphorescence)produced when it is returned from a triplet excitation state to a groundstate. A light emitting device of the present invention may use any oneof the above light emissions or both light emissions. Note that alllayers formed between the anode and the cathode of the OLED is definedas an organic light emitting layer in this specification. The organiclight emitting layer includes, specifically, a light emitting layer, ahole injection layer, an electron injection layer, a hole transportlayer, and an electron transport layer. Fundamentally, the OLED has astructure in which the anode, the light emitting layer, and the cathodeare laminated in order. In addition to such a structure, there is thecase where the OLED has a structure in which the anode, the holeinjection layer, the light emitting layer, and the cathode are laminatedin order or a structure in which the anode, the hole injection layer,the light emitting layer, the electron transport layer, and the cathodeare laminated in order.

After the state shown in FIG. 11A is obtained by the above method, asupport 608 is bonded to through a bonding layer 607 (FIG. 11B). In thisembodiment, a plastic substrate is used as the support 608.Specifically, a resin substrate which has a thickness of 10 μm or moreand is made of, for example, PES (polyether sulfone), PC(polycarbonate), PET (polyethylene terephthalate), or PEN (polyethylenenaphthalate) can be used as the support. With respect to these plasticsubstrates, an effect of preventing entrance of a substance fromexternal such as moisture or oxygen which promotes deterioration of anorganic compound layer is small. Thus, for example, a single layer madeof a material selected from aluminum nitride (AlN), aluminum nitrideoxide (AlN_(X)O_(Y) (X>Y)), aluminum oxynitride (AlN_(X)O_(Y) (X<Y)),aluminum oxide (Al₂O₃), and beryllium oxide (BeO), or a laminate ofthose is preferably provided to cover the support which is the plasticsubstrate to obtain a structure for sufficiently preventing entrance ofa substance from external such as moisture or oxygen which promotesdeterioration of an organic compound layer. Note that, when aluminumnitride oxide (AlN_(X)O_(Y) (X>Y)) is used, it is desirable that aconcentration of nitrogen contained in the film is 10 atoms % to 80atoms %. For example, the MN film is formed by a sputtering method usingan aluminum nitride (AlN) target having, preferably, purity of 2N ormore in an atmosphere including a mixture of an argon gas and a nitrogengas. The film may also be formed using an aluminum (Al) target in anatmosphere including a nitrogen gas.

Also, a sample obtained by sealing an OLED with a film substrate towhich an AlN_(X)O_(Y) film having a film thickness of 200 nm is providedand a sample obtained by sealing an OLED with a film substrate to whichan SiN film having a film thickness of 200 nm is provided are prepared.Then, a test for examining a time variation in a water vapor atmosphereheated to 85° C. is conducted. As a result, as compared with the sampleusing the SiN film, the OLED in the sample using the AlN_(X)O_(Y) filmhas a longer life and light emission can be produced for a longer time.From the test result, it can be read that the AlN_(X)O_(Y) film is amaterial film capable of preventing entrance of a substance fromexternal such as moisture or oxygen which promotes deterioration of anorganic compound layer as compared with the SiN film.

Also, a structure in which only one surface of a plastic substrate iscovered with these films (each made of AlN, AlN_(X)O_(Y) (X>Y), or thelike) may be used. In addition, these films (each made of MN,AlN_(X)O_(Y) (X>Y), or the like) may be formed on the interlayerinsulating film 606.

Also, FIG. 18 shows transmittances of the AlN film and the AlN_(X)O_(Y)(X>Y) film, each having the film thickness of 100 nm. As shown in FIG.18, these films (each made of AlN, AlN_(X)O_(Y) (X>Y), or the like) havevery high transparent property (transmittance is 80% to 91.3% in avisible light range) and thus do not hinder light emission by a lightemitting element. In addition, the films (each made of AlN, AlN_(X)O_(Y)(X>Y), or the like) have a high thermal conductivity. Thus, there is aheat radiation effect.

Note that, when the support 608 and the bonding layer 607 are located onan observer side (light emitting device user side) in the case wherethey are viewed from the OLED, it is necessary that they may be made ofa light transmitting material.

Next, any one of processings in Embodiment Modes 1 to 3 is performed topartially reduce the contact property, and then the substrate 600 towhich the first material layer 601 is provided is peeled by physicalmeans (FIG. 11C). Here, the second material layer 602 has compressionstress and the first material layer 601 has tensile stress. Thus, thesubstrate can be peeled by relatively small force (for example, by thehand of a person, by a blowing pressure of a gas blown from a nozzle, byultrasound, or the like).

Next, a resultant layer after peeling is bonded to a transfer body 610through a bonding layer 609 made of an epoxy resin or the like (FIG.11D). In this embodiment, a plastic film substrate is used as thetransfer body 610 for weight reduction.

As in the case of the support, it is preferable that a single layer madeof a material selected from aluminum nitride (MN), aluminum nitrideoxide (AlN_(X)O_(Y) (X>Y)), aluminum oxynitride (AlN_(X)O_(Y) (X<Y)),aluminum oxide (Al₂O₃), and beryllium oxide (BeO), or a laminate ofthose is provided to the transfer body which is the plastic substrate tosufficiently prevent entrance of a substance from external such asmoisture or oxygen which promotes deterioration of an organic compoundlayer.

Thus, a flexible light emitting device sandwiched by the flexiblesupport 608 and the flexible transfer body 610 can be obtained. Notethat, when the support 608 and the transfer body 610 are each made ofthe same material, the thermal expansion coefficients become equal toeach other. Therefore, the influence of stress distortion due totemperature variation can be reduced.

Then, if necessary, the flexible support 608 and the flexible transferbody 610 are divided into desired shapes. Then, an FPC (not shown) isbonded by a known technique.

Embodiment 5

A structure of the EL module obtained by Embodiment 4 will be describedusing a top view and a cross sectional view of FIGS. 12A and 12B. A filmsubstrate 900 a corresponds to the transfer body 610 in Embodiment 4. Anexample in which a film having thermal conductivity 900 b (typically, analuminum nitride film or aluminum oxynitride film) is provided on thefilm substrate 900 a is indicated here.

FIG. 12A is a top view showing the EL module and FIG. 12B is a crosssectional view obtained by cutting FIG. 12A along a line A-A′. In FIG.12A, the film having thermal conductivity 900 b is provided to theflexible film substrate 900 a (for example, a plastic substrate), and afilm having compression stress 901 (for example, a silicon oxide film)is bonded thereto through a bonding layer 923. A pixel portion 902, asource side driver circuit 904, and a gate side driver circuit 903 areformed on the film having compression stress 901. The pixel portion andthe driver circuits can be obtained in accordance with the aboveEmbodiment 1.

The above film having thermal conductivity 900 b indicates a singlelayer made of a material selected from aluminum nitride (AlN), aluminumnitride oxide (AlN_(X)O_(Y) (X>Y)), aluminum oxynitride (AlN_(X)O_(Y)(X<Y)), aluminum oxide (Al₂O₃), and beryllium oxide (BeO), or a laminateof those. When the film having thermal conductivity 900 b is provided,heat generated in the element can be radiated and it can be sufficientlyprevented that a substance such as moisture or oxygen which promotesdeterioration of an organic compound layer is entered from external.

Also, reference numeral 918 denotes an organic resin and 919 denotes aprotective film. The pixel portion and the driver circuit portion arecovered with the organic resin 918. The organic resin is covered withthe protective film 919. Sealing is conducted using a cover member 920through a bonding layer. The cover member 920 is bonded as the supportbefore peeling. In order to suppress deformation due to heat, externalforce, and the like, it is desirable that a substrate having the samematerial as the film substrate 900 a, for example, a plastic substrateis used as the cover member 920. Here, a substrate processed into aconcave shape (3 μm to 10 μm in depth) as shown in FIG. 12B is used. Itis preferable that the substrate is further processed to form a concaveportion (50 μm to 200 μm in depth) capable of locating a dry agent 921.In addition, when the EL module is manufactured by a multiple gangprinting, the substrate and the cover member may be bonded to each otherand then divided using a CO₂ laser or the like so as to align endsurfaces thereof.

Note that reference numeral 908 denotes a wiring for transferringsignals inputted to the source side driver circuit 904 and the gate sidedriver circuit 903. The wiring 908 receives a video signal and a clocksignal from an FPC (flexible printed circuit) 909 as an external inputterminal. Note that only the FPC is shown here. However, a printedwiring board (PWB) may be attached to the FPC. The light emitting devicein this specification includes not only a main body of the lightemitting device but also a light emitting device to which the FPC or thePWB is attached.

Next, the cross sectional structure will be described using FIG. 12B.The film having thermal conductivity 900 b is provided on the filmsubstrate 900 a, the film having compression stress 901 is boned theretothrough the bonding layer 923, and is an insulating film 910 is formedthereon. The pixel portion 902 and the gate side driver circuit 903 areformed over the insulating film 910. The pixel portion 902 is composedof a plurality of pixels each including a current control TFT 911 and apixel electrode 912 electrically connected with the drain thereof. Inaddition, the gate side driver circuit 903 is composed of a CMOS circuitin which an n-channel TFT 913 and a p-channel 914 are combined.

These TFTs (including 911, 913, and 914) are preferably manufactured inaccordance with the n-channel TFT and the p-channel TFT in the aboveEmbodiment 1.

Note that, after the pixel portion 902, the source side driver circuit904, and the gate side driver circuit 903 are formed on the samesubstrate in accordance with Embodiments 1 and 2, a support (here, acover member) is bonded in accordance with Embodiment 2 and then asubstrate (not shown) is peeled. Then, the film substrate 900 a on whichthe film having thermal conductivity 900 b is provided is bonded throughthe bonding layer 923.

Also, when the cover member 920 having the concave shape shown in FIG.12B is used, the cover member 920 as the support is bonded. Note that awiring lead terminal portion (connection portion) has only theinsulating film 910 at the time of peeling, thereby lowering amechanical strength. Thus, it is desirable that the FPC 909 is bondedbefore peeling and is fixed using the organic resin 922.

Note that, a material which not only blocks diffusion of an impurity ionsuch as an alkali metal ion or an alkali earth metal ion but alsoactively absorbs an impurity ion such as an alkali metal ion or analkali earth metal ion is preferably used for the insulating filmprovided between the TFT and the OLED. Further, a material resistant toa later process temperature is suitable. As an example of a material fitto such conditions, there is a silicon nitride film including a largeamount of fluorine. A concentration of fluorine contained in the siliconnitride film is preferably set to be 1×10¹⁹/cm³ or more. Preferably, acomposition proportion of fluorine in the silicon nitride film is set tobe 1% to 5%. Fluorine in the silicon nitride film is bonded to an alkalimetal ion, an alkali earth metal ion, or the like, thereby beingabsorbed in the film. In addition, as another example, there is anorganic resin film including a particle which is made of an antimony(Sb) compound, a tin (Sn) compound, or an indium (In) compound forabsorbing an alkali metal ion, an alkali earth metal ion, or the like,for example, an organic resin film including an antimony pentoxideparticle (Sb₂O₅.nH₂O). Note that the organic resin film includes aparticle with an average grain size of 10 nm to 20 nm and has very hightransparent property. The antimony compound represented by the antimonypentoxide particle is easy to absorb an impurity ion such as an alkalimetal ion or an alkali earth metal ion.

The pixel electrode 912 serves as a cathode of the light emittingelement (OLED). Banks 915 are formed at both ends of the pixel electrode912. An organic compound layer 916 and an anode 917 of the lightemitting element are formed on the pixel electrode 912.

As the organic compound layer 916, an organic compound layer (layer forcausing light emission and carrier transfer therefor) formed by freelycombining a light emitting layer, a charge transport layer, and a chargeinjection layer is preferably used. For example, a low molecular systemorganic compound material or a polymer system organic compound materialis preferably used. In addition, as the organic compound layer 916, athin film made of a light emitting material in which light emission(fluorescence) is produced by singlet excitation (singlet compound) or athin film made of a light emitting material in which light emission(phosphorescence) is produced by triplet excitation (triplet compound)can be used. In addition, an inorganic material such as silicon carbidecan be used for the charge transport layer and the charge injectionlayer. known materials can be used as the organic materials and theinorganic material.

The anode 917 also serves as a wiring common to all pixels and iselectrically connected with the FPC 909 through the connection wiring908. Further, all elements contained in the pixel portion 902 and thegate side driver circuit 903 are covered with the anode 917, the organicresin 918, and the protective film 919.

Note that, it is preferable that a material which is transparent orsemitransparent with respect to visible light is used as the organicresin 918. In addition, it is desirable that the organic resin 918 is amaterial which does not transmit moisture and oxygen.

Also, after the light emitting element is completely covered with theorganic resin 918, it is preferable that at least the protective film919 is provided on the surface (exposed surface) of the organic resin918 as shown in FIGS. 12A and 12B. The protective film may be formed onthe entire surface including the rear surface of the substrate. Here, itis required that the protective film is not formed on a portion to whichthe external input terminal (FPC) is provided. It may be made so as notto form the protective film using a mask. Or, it may be made so as notto form the protective film by covering the external input terminalportion with a tape made of Teflon to (registered trademark) or the likeused as a masking tape in a CVD apparatus. A film having the samethermal conductivity as the film 900 b may be used as the protectivefilm 919.

When the light emitting element is sealed with the protective film 919in the above structure, the light emitting element can be completelyshielded from external and it can be prevented that a substance such asmoisture or oxygen which promotes deterioration due to oxidation of anorganic compound layer is entered from external. In addition, heat canbe diffused by the film having the thermal conductivity 900 b. Thus, alight emitting device having high reliability can be obtained.

Also, a structure in which the pixel electrode is used as the anode, andthe organic compound layer and the cathode are laminated to producelight emission in a direction opposite to the light emitting directionshown in FIG. 12 may be used. FIG. 13 shows an example. Note that thetop view is the same drawing as FIG. 12A and is omitted here.

The cross sectional structure shown in FIG. 13 will be described below.A film having thermal conductivity 1000 b is provided to a filmsubstrate 1000 a and an insulating film 1010 is formed thereover. Apixel portion 1002 and a gate side driver circuit 1003 are formed overthe insulating film 1010. The pixel portion 1002 is composed of aplurality of pixels each including a current control TFT 1011 and apixel electrode 1012 electrically connected with the drain thereof. Notethat, after a layer to be peeled formed on the substrate is peeled inaccordance with Embodiment Modes, the film substrate 1000 a to which thefilm having the thermal conductivity 1000 b is provided is bondedthrough a bonding layer 1023. In addition, A gate side driver circuit1003 is composed of a CMOS circuit in which an n-channel TFT 1013 and ap-channel TFT 1014 are combined.

The above film having the thermal conductivity 1000 b indicates a singlelayer made of a material selected from aluminum nitride (AlN), aluminumnitride oxide (AlN_(X)O_(Y) (X>Y)), aluminum oxynitride (AlN_(X)O_(Y)(X<Y)), aluminum oxide (Al₂O₃), and beryllium oxide (BeO), or a laminateof those. When the film having the thermal conductivity 1000 b isprovided, heat generated in the element can be radiated and it can besufficiently prevented that a substance such as moisture or oxygen whichpromotes deterioration of an organic compound layer is entered fromexternal.

These TFTs (including 1011, 1013, and 1014) are preferably manufacturedin accordance with the n-channel TFT 201 and the p-channel TFT 202 inthe above Embodiment 1.

The pixel electrode 1012 serves as an anode of the light emittingelement (OLED). Banks 1015 are formed at both ends of the pixelelectrode 1012. An organic compound layer 1016 and a cathode 1017 of thelight emitting element are formed on the pixel electrode 1012.

The anode 1017 also serves as a wiring common to all pixels and iselectrically connected with a FPC 1009 through a connection wiring 1008.Further, all elements contained in the pixel portion 1002 and the gateside driver circuit 1003 are covered with the anode 1017, an organicresin 1018, and a protective film 1019. A film having the same thermalconductivity as the film 1000 b may be used as the protective film 1019.It is bonded to a cover member 1020 through a bonding layer. A concaveportion is provided to the cover member and a dry agent 1021 is locatedtherein.

When the cover member 1020 having the concave shape shown in FIG. 13 isused, the cover member 1020 as the support is bonded. Note that a wiringlead terminal portion (connection portion) has only the insulating film1010 at the time of peeling, thereby lowering a mechanical strength.Thus, it is desirable that the FPC 1009 is bonded before peeling and isfixed using an organic resin 1022.

Also, in FIG. 13, the pixel electrode is used as the anode, and theorganic compound layer and the cathode are laminated. Thus, a lightemitting direction becomes a direction indicated by an arrow in FIG. 13.

Although, the example of a top gate TFT is described here, the presentinvention can be applied independent of the TFT structure. The presentinvention can also be applied to, for example, a bottom gate (inversestaggered) TFT or a staggered TFT.

Embodiment 6

The example in which the top gate TFT is used is described in Embodiment5. However, a bottom gate TFT can also be used. An example in which thebottom gate TFT is used is shown in FIG. 14.

As shown in FIG. 14, the bottom gate structure is used for an n-channelTFT 1113, a p-channel TFT 1114, and an n-channel TFT 1111. The bottomgate structure is preferably obtained by using a known technique. Notethat each active layer of these TFTs may be a semiconductor film havinga crystalline structure (made of polysilicon or the like) or asemiconductor film having an amorphous structure (made of amorphoussilicon or the like).

Also, in FIG. 14, reference numeral 1100 a denotes a flexible filmsubstrate (for example, a plastic substrate), 1100 b denotes a filmhaving thermal conductivity, 1101 denotes a film having compressionstress (for example, silicon oxide film), 1102 denotes a pixel portion,1103 denotes a gate side driver circuit, 1110 denotes an insulatingfilm, 1112 denotes a pixel electrode (cathode), 1115 denotes banks, 1116denotes an organic compound layer, 1117 denotes an anode, 1118 denotesan organic resin, 1119 denotes a protective film, 1120 denotes a covermember, 1121 denotes a dry agent, 1122 denotes an organic resin, and1123 denotes a bonding layer.

The above film having the thermal conductivity 1100 b indicates a singlelayer made of a material selected from aluminum nitride (AlN), aluminumnitride oxide (AlN_(X)O_(Y) (X>Y)), aluminum oxynitride (AlN_(X)O_(Y)(X<Y)), aluminum oxide (Al₂O₃), and beryllium oxide (BeO), or a laminateof those. When the film having the thermal conductivity 1100 b isprovided, heat generated in the element can be radiated and it can besufficiently prevented that a substance such as moisture or oxygen whichpromotes deterioration of an organic compound layer is entered fromexternal. In addition, a film having the same thermal conductivity asthe film 1100 b may be used as the protective film 1119.

Also, the structure except for the n-channel TFT 1113, the p-channel TFT1114, and the n-channel TFT 1111 is the same as that of Embodiment 5 andthe description is omitted here.

Embodiment 7

The driver circuit portion and the pixel portion fabricated byimplementing the present invention can be utilized for various modules(active matrix liquid crystal module, active matrix EL module and activematrix EC module). Namely, all of the electronic apparatuses arecompleted by implementing the present invention.

Following can be given as such electronic apparatuses: video cameras,digital cameras, head mounted displays (goggle type displays), carnavigation systems, projectors, car stereos, personal computers,portable information terminals (mobile computers, mobile phones orelectronic books etc.). Examples of these are shown in FIGS. 15A to 15Fand 16A to 16C.

FIG. 15A is a personal computer which comprises a main body 2001, animage input section 2002; a display section 2003, a keyboard 2004 andthe like. The present invention is applicable to the display section2003.

FIG. 15B is a video camera which comprises a main body 2101, a displayis section 2102, a voice input section 2103, operation switches 2104, abattery 2105, an image receiving section 2106 and the like. The presentinvention is applicable to the display section 2102.

FIG. 15C is a mobile computer which comprises a main body 2201, a camerasection 2202, an image receiving section 2203, operation switches 2204,a display section 2205 and the like. The present invention is applicableto the display section 2205.

FIG. 15D is a goggle type display which comprises a main body 2301, adisplay section 2302, an arm section 2303 and the like. The presentinvention is applicable to the display section 2302.

FIG. 15E is a player using a recording medium which records a program(hereinafter referred to as a recording medium) which comprises a mainbody 2401, a display section 2402, a speaker section 2403, a recordingmedium 2404, operation switches 2405 and the like. This apparatus usesDVD (Digital Versatile Disc), CD, etc. for the recording medium, and canperform music appreciation, film appreciation, games and use forInternet. The present invention is applicable to the display section2402.

FIG. 15F is a digital camera which comprises: a main body 2501, adisplay section 2502, a view finder 2503, operation switches 2504, animage receiving section (not shown in the figure) and the like. Thepresent invention is applicable to the in display section 2502.

FIG. 16A is a mobile phone which comprises a main body 2901, a voiceoutput section 2902, a voice input section 2903, a display section 2904,operation switches 2905, an antenna 2906, an image input section (CCD,image sensor, etc.) 2907 and the like. The present invention isapplicable to the display section 2904.

FIG. 16B is a portable book (electronic book) which comprises a mainbody 3001, display sections 3002 and 3003, a recording medium 3004,operation switches 3005, an antenna 3006 and the like. The presetinvention is applicable to the display sections 3002 and 3003.

FIG. 16C is a display which comprises a main body 3101, a supportingsection 3102, a display section 3103 and the like. The present inventionis applicable to the display section 3103.

In addition, the display shown in FIG. 16C is small and medium type orlarge type, for example, 5 to 20 inches screen display. Moreover, it ispreferable to mass-produce by performing a multiple pattern using 1×1 msubstrate to form such sized display section.

As described above, the applicable range of the present invention isvery large and the invention can be applied to methods of electronicapparatuses of various areas. Note that the electronic devices of thisembodiment can be achieved by utilizing any combination of constitutionsin Embodiments 1 to 6.

Embodiment 8

In this embodiment, an example in which an electrophoretic displaydevice is used as the display portion described in Embodiment 7 isshown. Typically, it is applied to the display portion 3002 or 3003 ofthe portable book (electronic book) shown in FIG. 16B.

The electrophoretic display device (electrophoretic display) is alsocalled an electronic paper and there is an advantage that it is easy toread like paper. In addition, a thin and light weight device with lowerconsumption power as compared with another display device can beobtained.

With respect to the electrophoretic display, various types can beconsidered. One is produced by dispersing a plurality of micro capsuleswhich contain a first particle having a positive charge and a secondparticle having a negative charge in a solvent or a solute. Then, whenan electric field is applied to the micro capsules, particles in therespective micro capsules are moved in opposite directions to displayonly color of particles collected in one side. Note that the firstparticle or the second particle includes pigment and they do not move inthe case where no electric field is generated. In addition, it isassumed that the color of the first particle and that of the secondparticle are different from each other (including the case where it iscolorless).

Thus, the electrophoretic display is a display utilizing a so-calleddielectric migration effect such as a substance having a high dielectricconstant is moved to a high electric field region. In the case of theelectrophoretic display, a polarizing plate and a counter electrodewhich are required for a liquid crystal display device is unnecessary.Thus, a thickness and a weight are reduced in half.

When the above micro capsules are dispersed in a solvent, it is calledan electronic ink. The electronic ink can be printed on the surface ofglass, plastic, a cloth, a paper, and the like. In addition, when acolor filter or a particle having pigment is used, color display ispossible.

When the plurality of micro capsules are located on an active matrixsubstrate as appropriate so as to be sandwiched between two electrodes,an active matrix display device is completed. Thus, when an electricfield is applied to the micro capsules, display can be conducted. Forexample, the active matrix substrate obtained in Embodiment 1 can beused. The electronic ink can be directly printed on a plastic substrate.When an active matrix type is used, as compared with the case where anis element is formed on a plastic film which is sensitive to heat and anorganic solvent, a process margin is preferably improved when an elementand an electronic ink are formed on a glass substrate, and then theglass substrate is peeled in accordance with Embodiment Modes 1 to 3 andEmbodiment 2 before being bonded to a plastic substrate.

Note that as the first particle and the second particle in the microcapsules, a conductor material, an insulator material, a semiconductormaterial, a magnetic material, a liquid crystal material, aferroelectric material, an electroluminescence material, anelectrochromic material, and an electrophoretic material, or a compoundmaterial thereof is preferably used.

According to the present invention, not only a layer to be peeled havinga small area but also a layer to be peeled having a large area can bepeeled over the entire surface at a high yield.

In addition, according to the present invention, the layer to be peeledcan be easily peeled by the physical means, for example, by the hand ofa person. Thus, it may be a process suitable to mass production. Inaddition, when a manufacturing apparatus for peeling a layer to bepeeled is produced for mass production, a large size manufacturingapparatus can be produced at a low cost.

What is claimed is:
 1. A display device comprising: a first flexiblesubstrate; a first bonding layer on and in contact with the firstflexible substrate; a film comprising an organic material, the film onand in contact with the first bonding layer; a first insulating film onand in contact with the film; a thin film transistor over the firstinsulating film, the thin film transistor including a semiconductor filmand a gate electrode with a gate insulating film interposedtherebetween; a second insulating film over the thin film transistor; apixel electrode over the second insulating film, the pixel electrodebeing electrically connected to the thin film transistor; a bank over anedge portion of the pixel electrode; a light emitting layer comprisingan organic light emitting material over the pixel electrode, the lightemitting layer capable of emitting red light, green light, or bluelight; a second electrode over the light emitting layer; and a thirdinsulating film on and in contact with the second electrode.
 2. Thedisplay device according to claim 1, wherein the first insulating filmcomprises silicon and oxygen.
 3. The display device according to claim1, wherein the semiconductor film comprises silicon.
 4. The displaydevice according to claim 1, wherein the second insulating filmcomprises resin.
 5. The display device according to claim 1, wherein thepixel electrode is an anode.
 6. A display device comprising: a firstflexible substrate; a first bonding layer on and in contact with thefirst flexible substrate; a first film comprising an organic material,the first film on and in contact with the first bonding layer; a firstinsulating film on and in contact with the film; a thin film transistorover the first insulating film, the thin film transistor including asemiconductor film and a gate electrode with a gate insulating filminterposed therebetween; a second insulating film over the thin filmtransistor; a pixel electrode over the second insulating film, the pixelelectrode being electrically connected to the thin film transistor; abank over an edge portion of the pixel electrode; a light emitting layercomprising an organic light emitting material over the pixel electrodethe light emitting layer capable of emitting red light, green light, orblue light; a second electrode over the light emitting layer; an thirdinsulating film on and in contact with the second electrode; a secondbonding layer over the third insulating film; and a second filmcomprising an organic material, the second film on and in contact withthe second bonding layer.
 7. The display device according to claim 6,wherein the first insulating film comprises silicon and oxygen.
 8. Thedisplay device according to claim 6, wherein the semiconductor filmcomprises silicon.
 9. The display device according to claim 6, whereinthe second insulating film comprises resin.
 10. The display deviceaccording to claim 6, wherein the pixel electrode is an anode.
 11. Adisplay device comprising: a first flexible substrate; a first bondinglayer on and in contact with the first flexible substrate; a filmcomprising an organic material, the film on and in contact with thefirst bonding layer; a first insulating film on and in contact with thefilm; a first thin film transistor in a pixel portion over the firstinsulating film, the first thin film transistor including a firstsemiconductor film and a first gate electrode with a first gateinsulating film interposed therebetween; a second thin film transistorin a driver circuit portion over the first insulating film, the secondthin film transistor including a second semiconductor film and a secondgate electrode with a second gate insulating film interposedtherebetween; a second insulating film over the first thin filmtransistor and the second thin film transistor; a pixel electrode overthe second insulating film, the pixel electrode being electricallyconnected to the first thin film transistor; a bank over an edge portionof the pixel electrode; a light emitting layer comprising an organiclight emitting material over the pixel electrode; a second electrodeover the light emitting layer and the second thin film transistor; and athird insulating film on and in contact with the second electrode. 12.The display device according to claim 11, wherein the first insulatingfilm comprises silicon and oxygen.
 13. The display device according toclaim 11, wherein each of the first semiconductor film and the secondsemiconductor film comprises silicon.
 14. The display device accordingto claim 11, wherein the second insulating film comprises resin.
 15. Thedisplay device according to claim 11, wherein the pixel electrode is ananode.
 16. The display device according to claim 11, wherein the lightemitting layer is capable of emitting red light, green light, or bluelight.
 17. A display device comprising: a first flexible substrate; afirst bonding layer on and in contact with the first flexible substrate;a film comprising an organic material, the film on and in contact withthe first bonding layer; a first insulating film on and in contact withthe film; a first thin film transistor in a pixel portion over the firstinsulating film, the first thin film transistor including a firstsemiconductor film and a first gate electrode with a first gateinsulating film interposed therebetween; a second thin film transistorin a driver circuit portion over the first insulating film, the secondthin film transistor including a second semiconductor film and a secondgate electrode with a second gate insulating film interposedtherebetween; a second insulating film over the first thin filmtransistor and the second thin film transistor; a pixel electrode overthe second insulating film, the pixel electrode being electricallyconnected to the first thin film transistor; a bank over an edge portionof the pixel electrode; a light emitting layer comprising an organiclight emitting material over the pixel electrode; a second electrodeover the light emitting layer and the second thin film transistor; athird insulating film on and in contact with the second electrode; asecond bonding layer over the third insulating film; and a second filmcomprising an organic material, the second film on and in contact withthe second bonding layer.
 18. The display device according to claim 17,wherein the first insulating film comprises silicon and oxygen.
 19. Thedisplay device according to claim 17, wherein each of the firstsemiconductor film and the second semiconductor film comprises silicon.20. The display device according to claim 17, wherein the secondinsulating film comprises resin.
 21. The display device according toclaim 17, wherein the pixel electrode is an anode.
 22. The displaydevice according to claim 17, wherein the light emitting layer iscapable of emitting red light, green light, or blue light.